None of the reproductively active females in MLR were positive for chlamydia, while nearly all of the reproductively inactive females had the infection.
|
|
Women have a lot more to lose reproductively by committing to the wrong man.
|
|
As a result, women have been subjugated physically, emotionally, economically, and reproductively for millennia.
|
|
But the non-queen, or "subordinate," naked mole rat females that care for the babies are reproductively suppressed.
|
|
With the notable exception of killer whales, the females of most species die when they stop being reproductively useful.
|
|
The females that were exposed to heat waves were about as reproductively successful as the control group of females.
|
|
If these kiwi remained reproductively isolated, they could qualify as a species; however, that's something researchers just don't know yet.
|
|
This paper shows that after just two generations, they stopped breeding with other populations and have remained reproductively isolated ever since.
|
|
Though the tanks have barriers to prevent their eggs from escaping into the environment, FDA said the fish are reproductively sterile.
|
|
In particular, his team wanted to understand a fundamental mystery of human sexuality: Why humans have sex when they're not reproductively fertile.
|
|
We are quick to make it a problem for men, and not so much women, because of heteronormative and reproductively focused definitions of sex.
|
|
From this point it is a long, slow road to recovery – even those corals that survive will remain metabolically and reproductively compromised for months.
|
|
Other infectious disease experts agree: Reproductively speaking, men -- not women -- have the most reason for concern after visiting a country with a large Zika outbreak.
|
|
A triploid is reproductively constipated because it can't divide three into two very well, but then when you get up to tetraploid again, the biology recovers.
|
|
Once it was a common sight on the East Coast, but today, the very existence of the entire species is at risk: fewer than 100 reproductively-active females remain.
|
|
"It tells us that warblers in general appear to be reproductively compatible over millions of years of independent evolution," Dave Toews, postdoctoral associate at the Cornell Lab of Ornithology, told Gizmodo.
|
|
So long as a genetic alteration could have been bred in a plant—say a simple deletion, base pair swap, or insertion from a reproductively compatible relative—it won't be regulated.
|
|
"Obese bears are healthier; in fact, they are more reproductively fit," said Heiko T. Jansen, a professor at the College of Veterinary Medicine at Washington State University who presented at the meetings.
|
|
Pillar coral, whose clusters of spiky fingers appear to reach up from the sea bed, is "reproductively extinct" off the Florida coast, says Keri O'Neil, chief coral scientist at the Florida Aquarium.
|
|
Some birds might prefer to learn from certain highly regarded individuals, regardless of how common a syllable is, while others might prefer reproductively advantageous behaviors, like singing songs that make them stand out.
|
|
"I want to see if that is playing a role in the difference between their odors, and see if that might be playing a role in why they're becoming reproductively isolated," she said.
|
|
It's lived by women who are "no longer economically, socially, sexually, or reproductively dependent on or defined by the men they marry" — or don't marry — and who are driving a progressive new political agenda.
|
|
Medullary bone is only around for three to four weeks in females who are reproductively mature, so you'd have to cut up a lot of dinosaur bones to have a good chance of finding this.
|
|
But New Jersey bears are, of course, almost all native, and they are reproductively more fruitful than the nine hundred thousand black bears elsewhere in North America, whose average number of cubs per birth is a bit above two.
|
|
Females who sample widely tend to be more reproductively successful (which is why a lioness may mate up to 100 times a day with different lions during oestrus), and those who jockey for dominance are often rewarded with more food.
|
|
For a new species to occur, it has to become reproductively isolated, or form a stable population that no longer freely mixes with its parent species, said Alfredo Barrera-Guzmán, who led the new research as a doctoral student at the University of Toronto Scarborough.
|
|
Most of these early blockchain innovators just took the original cryptocurrency's source code, made their preferred changes, and launched their alternative versions as distinct cryptocurrencies; it was as if they'd modified the DNA of an existing species to create a new, reproductively isolated branch of the family tree.
|
|
Reproductively active female naked mole rats tend to associate with unfamiliar males (usually non-kin), whereas reproductively inactive females do not discriminate. The preference of reproductively active females for unfamiliar males is interpreted as an adaptation for inbreeding avoidance. Inbreeding is avoided because it ordinarily leads to the expression of recessive deleterious alleles.
|
|
Among overwintered adults, 90% of females and 100% of males are reproductively active.
|
|
After a teneral period of several days, the adults become reproductively active and are able to reproduce again later, although they may become reproductively quiescent if eclosing late in the season. Total life span is one to two years on average.
|
|
"The Callistophytales (Pteridospermopsida). Reproductively sophisticated gymnosperms." Review of Palaeobotany and Palynology, 32: 103-121.
|
|
Coast mole offspring can become reproductively active within nine to ten months of birth.
|
|
Hence, Orbicella species are reproductively isolated by at least these two ways, allowing for species distinction and evolution.
|
|
Males and females mature sexually at around long, respectively. The average age of reproductively active individuals is 21 years.
|
|
Other sexual behaviour may be reproductively motivated (e.g. sex apparently due to duress or coercion and situational sexual behaviour) or non-reproductively motivated (e.g. interspecific sexuality, sexual arousal from objects or places, sex with dead animals, homosexual sexual behaviour, and bisexual sexual behaviour). When animal sexual behaviour is reproductively motivated, it is often termed mating or copulation; for most non-human mammals, mating and copulation occur at oestrus (the most fertile period in the mammalian female's reproductive cycle), which increases the chances of successful impregnation.
|
|
Reproductively active female naked mole-rats tend to associate with unfamiliar males (usually non-kin), whereas reproductively inactive females do not discriminate. The preference of reproductively active females for unfamiliar males is interpreted as an adaptation for avoiding inbreeding. When mice inbreed with close relatives in their natural habitat, there is a significant detrimental effect on progeny survival. In the house mouse, the major urinary protein (MUP) gene cluster provides a highly polymorphic scent signal of genetic identity that appears to underlie kin recognition and inbreeding avoidance.
|
|
Several of these such as aeruginosum are considered as full species as they are reproductively isolated and distinct in morphology.
|
|
Limited data on reproduction show some notable variation between individuals and islands. In two caves surveyed on Grande Comore in November 2006, all females were pregnant with single embryos with crown-rump lengths of , but none of the males were reproductively active. In another cave, none of the bats examined at the same time—all males—were reproductively active.
|
|
Mating occurs in mid to late summer. B. bohemicus shows a 1:1 offspring sex ratio, consistent with production of only reproductively active offspring.
|
|
Morphs often interbreed, but they can also be reproductively isolated and represent genetically distinct populations, which have been cited as examples of incipient speciation.
|
|
Zootaxa 1819: 25–39. Historically, these species were often not distinguished from T. piniperda, but they are reproductively isolated, which has consequences for pest control.
|
|
The Thai and Myanmar populations are morphologically identical, but their echolocation calls are distinct. It is not known whether the two populations are reproductively isolated.
|
|
Both polyandrous and polygynous mating occurs, and males contribute heavily to parental care. But typically, only one adult female in a group is reproductively active, and reproductively active females mate with multiple males if given the opportunity. Males carry and groom infants more than females do. Older siblings may also contribute to infant care, although infants prefer to be carried by their parents than their siblings.
|
|
Many of the species belonging to Scaphyglottis before the unification are also confusing and variable, forming various complexes of reproductively isolated groups that seem morphologically identical.
|
|
Dorsal view of a nonreproductive female Diacamma australe worker, lacking anterior thoracic gemmae (buds). Within gamergate colonies, all workers are born reproductively viable and are thus potential gamergates. Prior to differentiation as a gamergate, a dominant worker must physically inhibit its sisters. For example, in the case of Diacamma australe, the first female to become reproductively active will clip off the thoracic gemmae of her sisters, thus greatly reducing their sexual attractiveness.
|
|
Researchers have thought that because different indigobird species sing different songs, they must be reproductively isolated. However, when a paternity test was done between the differentspecies, it was found that the birds were not reproductively isolated. They concluded that indigobirds switch songs among several different hosts, but that this switching does not mean that the species are biologically different. In fact, they are very much related to one another in which they are not isolated from other species.
|
|
Giant groupers are diandric protogynous hermaphrodites, meaning that although some males develop from reproductively functional females other males start to produce sperm without ever having gone through a phase as a reproductive female.
|
|
It is suspected that this infraspecific karyotypic diversity indicates the existence of one or more cryptic species, despite the different forms being phenotypically identical, because the polyploid forms would essentially be reproductively isolated.
|
|
Many of these populations live in sympatry, yet are reproductively isolated. The fact that they are young species makes them prime candidate to study the evolutionary forces driving their ecological divergence and reproductive isolation.
|
|
Both of these strategies have proven, thus far, to be reproductively effective for the males practicing them, and adoption of these alternative mating strategies has contributed to the maintenance of a dimorphic male population.
|
|
The researchers suggested that the necrophilia was a reproductive strategy, offsetting the fitness cost of the female's death. This would make R. proboscidea the only species known to practice reproductively functional, rather than accidental, necrophilia.
|
|
The establishment of hybrid species requires the development of reproductive isolation against parental species. Allopolyploid species often have strong intrinsic reproductive barriers due to differences in chromosome number, and homoploid hybrids can become reproductively isolated from the parent species through assortment of genetic incompatibilities. However, both types of hybrids can become further reproductively isolated, gaining extrinsic isolation barriers, by exploiting novel ecological niches, relative to their parents. Hybrids represent the merging of divergent genomes and thus face problems arising from incompatible combinations of genes.
|
|
There is no pressure to compete or interbreed (two responses when resources are short). These types of kokanee salmon show the principal attributes of a biological species: they are reproductively isolated and show strong resources partitioning.
|
|
Each nest can have one or more queens and in addition there is a range of female sexual development. With that said, most females have the capability of becoming a queen, as most are reproductively viable.
|
|
These reproductively discrete groups, referred to as intersterility groups, have begun to be defined in Pleurotus. Many binomial names used in literature are now being grouped together as species complexes using this technique, and may change.
|
|
Spawning contractions occur every two or three minutes, with intense spawning ranging from thirty minutes to two and a half hours. Clams that do not respond to the spawning of neighboring clams may be reproductively inactive.
|
|
A maritime Canadian climate can lead to reduced duration of brood production, fewer workers per nest, and fewer reproductive bees. Additionally, nest foundresses may produce a mixture of workers and reproductively-capable bees based on these conditions.
|
|
Tiny feathery tips along the antenna pick up the slightest hint of pheromone released by females to guide males to their mates. Genes that allow for more refined antenna tips will lead to more reproductively fit males.
|
|
It is currently not clear whether this pathogen can reproduce sexually in nature and genetic work has suggested that the lineages of the two mating types might be isolated reproductively or geographically given the evolutionary divergence observed.
|
|
There are two reproductively isolated species of wood white called L. sinapis and L. reali. These two species can mate with each other (heterospecific mating), but it is in their best interest, for the viability and fecundity of their offspring, that they mate only within their species (conspecific mating). Male members of the two species try and court or mate with females of both species with equal frequency, but the females only mate with members of their own species. This female choice has caused the two species to diverge and become reproductively isolated.
|
|
Despite their easily confused coloration, these two species are able to exist in the same habitat range because they are reproductively isolated due to adaptations in the eyes of the butterflies that allow for better distinction between individuals.
|
|
Spawning occurs in shallow, muddy lagoons. Females lay about 20,000 to 150,000 buoyant eggs, each 0.4 millimetres in diameter. Females become mature at about , and males become mature at about . T. chatareus become reproductively active at 24 months.
|
|
None of the bats captured in one of the caves in April 2007 showed signs of reproductive activity. On Anjouan, no bats were reproductively active in two caves surveyed in late November 2006.Goodman et al., 2010, p.
|
|
Major caruncle, 5. Beard. During sexual behavior, these structures enlarge or become brightly colored. Animal sexual behaviour takes many different forms, including within the same species. Common mating or reproductively motivated systems include monogamy, polygyny, polyandry, polygamy and promiscuity.
|
|
Males are smaller ( SVL) than females ( SVL). Mean sizes reported for Taiwanese "Hylarana" latouchii are larger, respectively and SVL. "Hylarana" latouchii is reproductively active throughout the year in Taiwan. Antimicrobial peptides can be isolated from skin of "Hylarana" latouchii.
|
|
Adults feed on termites, and such small insects as crickets and arachnids such as spiders. The frog is strictly nocturnal. It lives about three years in the wild, but the female is reproductively active only for two breeding seasons.
|
|
Bolas spiders mate in late summer. In late fall, the female spider attaches several egg-sacs suspended in the vicinity of her retreat; each one is larger than herself and contains a few hundred eggs. Males emerge as reproductively capable adults.
|
|
However, it is now recognized as a subspecies of the Australasian bent- wing bat (Miniopterus orianae). There is evidence to suggest that it is reproductively isolated from the other Australian subspecies, and warrants elevation to its own species based on genetics.
|
|
The Bombus transversalis colony cycle is based on the season of the year. Colonies are formed during the wet season. During this time the colony is continually developing. When the dry season comes, they become reproductively active for a few months.
|
|
The young become reproductively active when seven weeks old and the life cycle is short. The introduced snake Boa constrictor preys on O. couesi on Cozumel. Parasites recorded on O. couesi in Veracruz include unidentified ticks, mites, fleas, and fly larvae.
|
|
Mayr, on the basis of an understanding of genes and direct observations of evolutionary processes from field research, introduced the biological species concept, which defined a species as a group of interbreeding or potentially interbreeding populations that are reproductively isolated from all other populations. Both Dobzhansky and Mayr emphasised the importance of subspecies reproductively isolated by geographical barriers in the emergence of new species. The palaeontologist George Gaylord Simpson helped to incorporate palaeontology with a statistical analysis of the fossil record that showed a pattern consistent with the branching and non-directional pathway of evolution of organisms predicted by the modern synthesis.
|
|
This is a medium-sized lizard with a relatively large head. Its scales are overlapping. The reproductively mature female ranges from snout-to-vent length (SVL). One sample of adult males had a mean SVL of , while another found a mean SVL of .
|
|
A recent study comparing 813 bp mtDNA sequences led to the split of the Oriental magpie from the Eurasian magpie. It has been reproductively isolated for longer even than the yellow-billed magpie (P. nuttalli) of North America. Proposed subspecies include P. p.
|
|
The trunk is patterned with the marks of leaves that have fallen away. The spines are distributed between these leaf scars on the trunk. The plant becomes reproductively mature at 9 to 10 years of age. Flowering occurs during the rainy season.
|
|
There is a negative correlation between the frequency of mimics and the "survivability" of both species involved. This implies that it is reproductively beneficial for both species if the models outnumber the mimics; this increases the negative interactions between predator and prey.
|
|
Nuttallia obscurata can live at least six years. They begin life as free- swimming plankton. This planktonic stage can last from 3 to 8 weeks before they settle to the bottom as recognizable clams. They become reproductively mature at one year old.
|
|
Reproductively active adult males had significantly (p < 0.05) larger home ranges than adult males with unenlarged testes. In black greasewood (Sarcobatus vermiculatus) habitat, however, there were no significant differences between male and female home ranges or between home ranges of reproductive and nonreproductive adult males.
|
|
Certain plant species, such as Tradescantia canaliculata and T. subaspera, are sympatric throughout their geographic distribution, yet they are reproductively isolated as they flower at different times of the year. In addition, one species grows in sunny areas and the other in deeply shaded areas.
|
|
D. synthetica are fertile and able to produce viable offspring. Hybrids of D. synthetica and D. melanogaster die early in their pupal stage and are unable to develop into adults. As a direct result, the populations of D. synthetica and D. melanogaster are reproductively isolated.
|
|
The Roanoke hogsucker's life cycle and reproduction has not been fully studied. Males are reproductively mature after one or two years and typically live for four years. Females mature in three years and typically live for five years. Spawning occurs early to mid-spring.
|
|
131 These animals, collected in late November, were in reproductive condition, with two females pregnant and a third lactating. M. griveaudi were reproductively active at the same time, suggesting that the reproductive seasons of the two do not differ significantly.Goodman et al., 2010, pp.
|
|
S. intermedius is oviparous. The female will start reproducing at the age of two and will lay a clutch of two eggs during the summer. It takes about 45 days for the eggs to hatch. Females are reproductively active over a 6-month period.
|
|
Bobcats remain reproductively active throughout their lives. The female raises the young alone. One to six, but usually two to four, kittens are born in April or May, after roughly 60 to 70 days of gestation. Sometimes, a second litter is born as late as September.
|
|
Florida sand skinks are most active in spring, during their mating season. They reach sexual maturity after one to two years and remain reproductively active for two to three years. About 55 days after mating, the female lays about two eggs, which hatch in June or July.
|
|
Genetic admixture is the presence of DNA in an individual from a distantly- related population or species, as a result of interbreeding between populations or species who have been reproductively isolated and genetically differentiated. Admixture results in the introduction of new genetic lineages into a population.
|
|
It is reproductively active throughout March and April. Mature eggs are orange and translucent. The fish are insectivorous, with analyzed gut contents containing Nematocera larvae, more specifically black fly (Simuliidae) and midge (Chironomidae) larvae. Significant numbers of mayfly (Ephemeroptera) and caddisfly (Trichoptera) nymphs were also found.
|
|
The BSC defines species as "groups of actually or potentially interbreeding natural populations, which are reproductively isolated from other such groups". From this perspective, each species is based on a property (reproductive isolation) that is shared by all the organisms in the species that objectively distinguishes them.
|
|
Great Basin pocket mice remain reproductively active through summer. Females produce one or two litters per year. Most first litters are delivered in May and second litters in August. Reports of average litter size have ranged from 3.9 in south-central Washington to 5.6 in Nevada.Hall, E. Raymond. 1946.
|
|
Sexual maturity is reached at approximately five to six weeks (range 34 – 90 days). Timing of sexual maturity, as well as dispersal age, depends on environmental factors (e.g. resource availability), social cues (e.g. the presence of older, reproductively active animals), as well as the animal’s developmental history (e.g.
|
|
2; Linzey and Hammerson, 2008 Young marsh rice rats and O. couesi become reproductively active when about 50 days old.Medellín and Medellín, 2006, p. 710; Wolfe, 1982, p. 2 The marsh rice rat, O. couesi, and O. gorgasi are known to be omnivores, eating both plant and animal material.
|
|
Lutzomyia arthrophora feed on both carbohydrates and blood. Females that feed on carbohydrates fare better reproductively than those that do not. After feeding on these sugar solutions L. arthrophora will wait twenty four hours before feeding again. Females will then feed on blood two to four days post eclosion.
|
|
Without eating or drinking, they can run for four or five hours. They are 10 times more active than ordinary mice in their home cage. They also live longer – up to three years of age – and are reproductively active for almost three years. In short, they are remarkable animals.
|
|
A major outcome of multi- generational natal philopatry is genetic divergence and, ultimately, speciation. Without genetic exchange, geographically and reproductively isolated populations may undergo genetic drift. Such speciation is most evident on islands. For mobile island-breeding animals, finding a new breeding location may be beyond their means.
|
|
They argued that as the fertile population is sexually reproducing, reproductively isolated, and emerged from a common origin (in contrast to A. × ebenoides, which arises through independent hybridization events, possibly followed by vegetative propagation), it is consistent with several well-accepted biological species concepts and is deserving of recognition.
|
|
It is more likely, though, that the cytodeme arose first complete with its suite of chromosomes and breeding patterns all intact and then, remaining constant in its fundamentals, it diversified into species sometimes so different as to merit generic distinction. Thus, in what may be termed the cytodeme adjunct to Darwinian theory, evolution becomes a two-stage process - first, the establishment of distinct cytodemes reproductively isolated both from one another and from all previously existing cytodemes; second, diversification within cytodeme to yield taxonomically recognisable (but not reproductively isolated) species. Whereas the second stage is Natural Selection as expounded by Darwin,Darwin,1859.On the Origin of Species by Means of Natural Selection.
|
|
Hermaphroditic fish are not reproductively functional. The sex composition of that population was 63.73% male, 22.22% hermaphroditic and 14.3% female. Spawning occurs throughout the year but peaks in the dry season and almost ceasesd during the rains. Most of these fish will not survive past the age of four years old.
|
|
The significance of responses of the genome to challenge. Science Vol. 226, pp. 792-801. Saltational speciation, also known as abrupt speciation, is the discontinuity in a lineage that occurs through genetic mutations, chromosomal aberrations or other evolutionary mechanisms that cause reproductively isolated individuals to establish a new species population.
|
|
This has caused the breed to be divided into three reproductively isolated groups: one in Croatia, one in Slovenia, and one in Italy. Today, they are primarily raised in permanent or semi-permanent herds. Although there are some variations in their characteristics, there is little genetic difference in these populations today.
|
|
Mating structures P. ramorum is heterothallic and has two mating types, A1 and A2, required for sexual reproduction. The European population is predominantly A1 while both mating types A1 and A2 are found in North America. Genetics of the two isolates indicate that they are reproductively isolated.Ivors, K., et al.
|
|
This species is ovoviviparous, with males brooding eggs in a brood pouch before giving birth to live young. It is reproductively active all year, with males and females reaching sexual maturity at respectively. Brood size can vary significantly, from 114 to 1764, with an average of 604.4 plus or minus 322.8.
|
|
The indri consumes little nontree vegetation. To feed, the indri plucks off a leaf or other plant part with its teeth. It uses its hands to pull tree branches closer to its mouth. Reproductively mature females have priority access to food sources, therefore they forage higher in the trees than males.
|
|
However, the extensive distribution of Z. c. intermedius (including S. Sulawesi, SE. Sulawesi, C. Lesser Sundas and small islands in between) is likely to contain more than one reproductively isolated population (cf. Z.c. intermedius and Z. c. flavissimus, with the latter now considered a distinct species, the Wakatobi white-eye (Z. flavissimus)).
|
|
The grousewinged backswimmer is bivoltine. Females of the first generation become adults and reproductively mature in July producing a second generation. The adults that become mature after July enter reproductive diapause which ends by late October. All N. undulata will overwinter in the adult stage and begin depositing eggs in the early spring.
|
|
They believed that the Swartkrans Paranthropus were reproductively isolated from Kromdraai Paranthropus and they eventually speciated. At this point in time, humans and ancestors were classified into the family Hominidae, and other apes into "Pongidae"; in 1950, Broom suggested separating early hominins into the subfamilies Australopithecinae (A. africanus and "P. transvaalensis"), "Paranthropinae" (P.
|
|
The head and body of these trout are silver in colour, with black dots. Red dots occur along the lateral line. Salmo lumi can grow to 38 cm length. The various trout of Ohrid are distinguished by their breeding time and habitat, and they are thus in practice reproductively isolated from each other.
|
|
A 1947 study found plants of R. emodi a chromosome count of 2n=22, but the same study found plants labelled as R. australe to be 2n=44. It is possible that this karyotypic diversity indicates the existence of one or more cryptic species, because the polyploid forms would essentially be reproductively isolated.
|
|
Longevity of a captive common treeshrew has been recorded as 12 yr and 5 mo. From October to December, common treeshrews are reproductively inactive. The mating season starts at the onset of the monsoon season in December and lasts until February. Oestrus and preoestrus behavior is characterized by adult males pursuing adult females.
|
|
Riodinidae have an unusual variety in chromosome numbers, only some very basal groups have the number typical for butterflies (between 29 and 31) or the number characteristic of Lycaenidae (23 to 24). Numbers between 9 and 110 occur. In some cases, representatives of a morphologically indistinguishable cryptospecies have different chromosome numbers and are reproductively isolated.
|
|
Of all the domesticated species of peppers, this is the least widespread and systematically furthest away from all others. It is reproductively isolated from other species of the genus Capsicum. A very notable feature of this species is its ability to withstand cooler temperatures than other cultivated pepper plants, although it cannot withstand frost.
|
|
Labor is divided between guarding and foraging females. The foraging female is the reproductively- dominant one, while the guarding females are either young pre-reproductive females or old formerly reproductive females. Young pre-productive females remain in the nest for up to two weeks. During this time they guard the entrance to the nest.
|
|
Pre- imaginal determination is the predominant theory as to why certain females become reproductively capable over others. There is a lack of queen-queen aggression that suggests that only workers are involved in the queen selection process.Noll, F.B., Zucchi R. 2002. Castes and the influence of the colony cycle in swarm-founding polistine wasps.
|
|
Weller's salamanders breed during the spring and fall. Courtship behaviors have been observed in captivity in October and April. The females are reproductively mature at 35 mm in length and tend to be older than 3 years when they become mature. The males can breed around 30 mm long at about 2-3 years old.
|
|
Previously, only female L. verruculosus lice were recovered during one of Harry Hoogstraal's collecting expeditions, making the female louse the better-described sex. However, it has been recently discovered that there are three sexes of this ectoparasite: male, female and an instar nymph which is morphologically and reproductively different from either male or female.
|
|
There have been at least two studies investigating the karyotypy of this species, both studies focussing on the synonym R. undulatum. Both 2n=22 and 2n=44 have been found. It is possible that this karyotypic diversity indicates the existence of one or more cryptic species, because the polyploid forms would essentially be reproductively isolated.
|
|
Nature (2012) vol. 487. Assortive mating reproductively isolates H. heurippa from its parental species. Melo did a study on the hybrid H. heurippa to determine its mating habits regarding preference between other hybrids and its parental species. The results showed H. heurippa chose to reproduce via backcrossing, while the parental species were highly unlikely to reproduce with the backcrosses.
|
|
Frederiksborgers are early-maturing, long-lived, and sound reproductively and structurally well into their old age. The greatest concern facing the health of the Frederiksborger is inbreeding due to a limited gene pool. However, studbook inspections are intended to safeguard the breed against weakness; a horse with a known genetic disorder is not approved to breed.
|
|
Most taxa differ morphologically from other taxa. Typically, closely related taxa differ much less than more distantly related ones, but there are exceptions to this. Cryptic species are species which look very similar, or perhaps even outwardly identical, but are reproductively isolated. Conversely, sometimes unrelated taxa acquire a similar appearance as a result of convergent evolution or even mimicry.
|
|
Splake grow more quickly than brook trout and become piscivorous sooner and are more tolerant of competitors than brook trout. The tiger trout is an intergeneric hybrid between the brook trout and the Eurasian brown trout (Salmo trutta). Tiger trout occur very rarely naturally, but are sometimes artificially propagated. Such crosses are almost always reproductively sterile.
|
|
As a member of the polistine wasp tribe Epiponini, B. lecheguana is a swarm-founding species. Their nests are polygynous, with reproductively active females numbering anywhere from 1% to possibly even 17% of a colony.Sugden, E. A. & McAllen, R. L. (1994). "Observations on foraging and nest biology of the Mexican honey wasp, Brachygastra mellifica (Say) in Texas (Vespidae: Polybiinae)".
|
|
Female fecundity is heavily influenced by reproduction and energetics. The ovarian cycle limits the potential of conception to a brief period of fertility roughly once a month. Successful egg maturation, fertilization, and implantation must be able to occur for a reproductively mature female to be fecund. Changes in energy levels, diet, and hormones can all interfere in this process.
|
|
One of the potential evolutionary outcomes of hybridisation is the establishment of a novel, reproductively isolated lineage, i.e., hybrid speciation. A hybrid species has an admixed genome and forms stable genetically distinct populations. Some researchers argue that evidence of a hybridization-derived basis for reproductive isolation should be an additional defining criterion for hybrid speciation, but see.
|
|
Whitebark pine has been found to live as long as 800 years, and foxtail pine, which is closely related to bristlecone pine (Pinus longaevis) has been estimated to live 2500–3000 years. Seedling establishment in the harsh subalpine environment is difficult, so evolution has instead favored long- lived individuals that are reproductively active for tens or hundreds of years.
|
|
Males start signaling first a week after they reach adulthood. Females become reproductively receptive 1–2 weeks about the males. After reproducing, females stay on one plant and oviposit their eggs continuously until they expire or until the first frost hits. Males live shorter than females and usually die shortly after mating a number of times.
|
|
Males typically roost alone or in small bachelor groups during the summer. Many males spend the summer near their winter hibernacula, while others migrate to other areas, similar to areas used by females. Females can mate during their first fall, but some do not breed until their second year. Males become reproductively active during their second year.
|
|
S. Mansuetus has been seen resting in the shade of trees on the island such as the Palo Verde. The rabbit becomes reproductively active in November. Being crepuscular the rabbit is most active from sunset till 2am, and 6am to 10am. The San José Island is home to one of the most diverse mammalian populations of off islands in Baja California.
|
|
As it signals the beginning of the breeding season, photoperiod may often signal its end. In the laboratory, an artificial short day-long night summer photoperiod caused gonadal shrinkage in Great Basin pocket mice. A favorable diet apparently overrides this effect, however, extending the breeding season. In nature, Great Basin pocket mice remain reproductively active through fall in years of favorable plant production.
|
|
Estuaries along the United States of America's eastern Atlantic coast houses many of the young sand tiger sharks. These estuaries are susceptible to non-point source pollution that is harmful to the pups. In Eastern Australia, the breeding population was estimated to be fewer than 400 reproductively mature animals, a number believed to be too small to sustain a healthy population.
|
|
In the rare occurrence of nests which contain more than one foundress, one individual will become the "guard". These guards are reproductively dominant individuals, while other individuals assume foraging duties. Single foundress nests, however, are left unguarded during foraging trips. As a result, these nests may be prone to experience conflict over nest ownership due to the occurrence of usurpation attempts.
|
|
Mimulus nudatus is a member of the Mimulus guttatus species complex, a group of closely related wildflower species that vary dramatically in mating system, life history and edaphic tolerance. Species in the M. guttatus complex are largely inter-fertile, with some notable exceptions. In particular, M. nudatus is reproductively isolated from other complex members via a postzygotic isolating barrier during seed development.
|
|
Rhabdomys is a seasonal breeder and reproductively active from spring to autumn. After a gestation period of 22–23 days, free-living females give birth to approximately five pups; captive females have slightly larger litters (e.g. 7.2 ±1.8). Pups begin to consume solid food at ten days, leave the nest from twelve days, and weaning occurs at around 16 days.
|
|
According to Smith's original account, the pincushion ray defends itself by striking with its thorn-covered tail, inflicting "severe and even dangerous wounds". Its diet is said to consist mainly of small eels. Like other stingrays, this species is aplacental viviparous, with a report of a female gestating two offspring. One recorded female across, from the Sanaga River, was reproductively immature.
|
|
The first proglottid stage is the immature stage, characterized by functional reproductive organs. The immature stage is the most anterior proglottid, and consists of anywhere between 200 and 300 proglottids. The mature proglottid is located medially to the other proglottids, and is reproductively functional and hermaphroditic. The most posterior proglottid is the gravid stage, and it is packed with eggs.
|
|
He believed later Paranthropus were morphologically distinct from earlier Paranthropus in the cave—that is, the Swartkrans Paranthropus were reproductively isolated from Kromdraai Paranthropus and the former eventually speciated. By 1988, several specimens from Swartkrans had been placed into P. crassidens. However, this has since been synonymised with P. robustus as the two populations do not seem to be very distinct. ;P.
|
|
Wedge-capped capuchins live in groups ranging from as few as 5 individuals to more than 30 individuals. The groups generally consist of one reproductively active adult male, several adult females and their offspring, and, in some cases, non-reproductive adult males. Juveniles generally make up about 50% of a groups population. The population structure is heavily skewed toward females.
|
|
Native to Europe, western Asia and probably North Africa, Forficula auricularia was introduced to North America in the early twentieth century and is currently spread throughout much of the continent. In North America, European earwigs comprise two sibling species, which are reproductively isolated.Wirth T., et al. (1998). Molecular and reproductive characterization of sibling species in the European earwig (Forficula auricularia).
|
|
The Atlantic winged oyster is often found attached to the stems of gorgonian corals by strong byssus threads. It often has algae and other organisms growing on the shell which make it well camouflaged. It is a filter feeder and is reproductively active all year round. The spat abundance varies and has four peaks in the period November to March.
|
|
The males present to the females a chorus (type of song) to try to attract a female for mating. This song ranges from a series of clicks to long, glottal sounds. This frog has an unusual characteristic of its reproduction. The male frog arrives at the breeding grounds before the female and establishes the oviposition site before the females become reproductively active.
|
|
The Portuguese dogfish is aplacental viviparous, with the female retaining eggs internally until they hatch. The embryos are sustained by yolk, and possibly also by uterine fluid secreted by the mother. Figueiredo et al. (2008) reported that there are two breeding seasons per year off Portugal, from January to May and from August to December, with only a fraction of the population reproductively active at a time.
|
|
Adult bull, females, and pups near Juneau, Alaska, the USA Reproductively mature male sea lions gather together mid-spring on traditional, well-defined reproductive rookeries,Gentry, R. L. (1970). "Social Behavior of the Steller’s Sea Lion". PhD Thesis, University of California, Santa Cruz, CA.Sandergen, F. E. (1970). 'Breeding and Maternal Behavior of the Steller’s Sea Lion (Eumetopias jubatus) in Alaska', M. S. Thesis, University of Alaska, College.
|
|
The weevil generally enters the cowpea pod through holes before harvest and lays eggs on the dry seed. The larvae burrow their way into the seed, feeding on the endosperm. The weevil develops into a sexually mature adult within the seed. An individual bruchid can lay 20–40 eggs, and in optimal conditions, each egg can develop into a reproductively active adult in 3 weeks.
|
|
Two important revisions – those of Linder in 1952 and Longhurst in 1955 – synonymised many taxa, and resulted in the recognition of only 11 species in the two genera. This taxonomy was accepted for decades, "even attaining the status of dogma". More recent studies, especially those employing molecular phylogenetics, have shown that the eleven currently recognised species conceal a greater number of reproductively isolated populations.
|
|
Gene flow occurs when individuals of the same species exchange genetic information through reproduction. Populations can maintain genetic diversity through migration. When a habitat becomes fragmented and reduced in area, gene flow and migration are typically reduced. Fewer individuals will migrate into the remaining fragments, and small disconnected populations that may have once been part of a single large population will become reproductively isolated.
|
|
In reproductively mature males, the head becomes elongated and prominent external teeth develop on the upper and lower jaws. Males with teeth tend to have larger gonads than those without. The coloration is a uniform pale white with a pinkish hue caused by subdermal capillaries, especially over anal fin pterygiophores (fin support bones). The operculum is pink due to the presence of the gills underneath.
|
|
Both the queen and workers possess the ability to reproduce. The queen suppresses the reproductive actions of workers through increased aggressive action against reproductively active workers and destruction of eggs laid by workers. In colonies still dominated by the queen, the vast majority of drones are derived from the queen. In colonies where the queen has died, roughly half the drones are born from workers.
|
|
The sawtail grouper is found at depths from . It is occurs in rocky reefs and it is commonest in areas where there are large boulders with gorgonians and black corals. This is a predatory species which feeds on small fishes in daytime and crustaceans at night. It is thought that it is a protogynous hermaphrodite with the older reproductively functional females changing to males.
|
|
These younger females can choose to leave their original nests for a more uncertain future (in terms of indirect and direct payoffs) to co-found a new nest. For older females who are more limited reproductively, however, the best and perhaps only option would be engage in risky foraging tasks to take care of others within their nests, thereby maximizing their own indirect fitness.
|
|
A common area of study in X. pubescens is its dominance hierarchy and guarding behavior. Colonies start and end with female takeover, either by daughters of the dominant female or by foreign intruders. There is only one reproductively active female in a colony at a time who suppresses the reproduction of other females in the nest. Males hold individual territories which females enter to mate.
|
|
This last behavior is unique to C. maculosus and one species of insect. The female develops a bright orange color on her throat when she is reproductively receptive. In threat display and flipping-over rejection, the female reveals her throat to communicate rejection to the male. Oviposition results in significant declines in steroid levels, a fading of color from the throat, and an increase in rejection behavior.
|
|
In biology, naturalisation (or naturalization) is any process by which a non- native organism or species spreads into the wild and its reproduction is sufficient to maintain its population. Such populations are said to be naturalised. Some populations do not sustain themselves reproductively, but exist because of continued influx from elsewhere. Such a non-sustaining population, or the individuals within it, are said to be adventive.
|
|
The process of genome stabilization during hybrid speciation and introgression. Both ecological selection pressures and selection to avoid intrinsic incompatibilities mould hybrid genomes. Depending on the balance between beneficial alleles and incompatibilities hybridisation can result either in an admixed taxon that is reproductively isolated from both parent taxa, or local introgression into a taxon that remains distinct in spite of occasional gene flow. RI abbreviates reproductive isolation.
|
|
Women who are 0.7 to 1.7 standard deviations below the mean female height have been reported to be the most reproductively successful, since fewer tall women get married compared to shorter women. However, in other ethnic groups, such as the Hadza, study has found that height is irrelevant in choosing a mate. In Middle English literature, 'tallness' is a characteristic of ideally beautiful women.
|
|
It also has a dark lower mandible and legs. Its song is buzzing and high pitched. The best distinction from the yellow-browed warbler is the more disyllabic call. While the eastern and western Hume's leaf warblers already show noticeable differences in mtDNA sequence and calls, their songs do not differ; they are reproductively isolated only by allopatry and not usually considered separate species.
|
|
A male tuatara named Henry, living at the Southland Museum and Art Gallery, is still reproductively active at 111 years of age. Tuatara reproduce very slowly, taking 10 to 20 years to reach sexual maturity. Mating occurs in midsummer; females mate and lay eggs once every four years. During courtship, a male makes his skin darker, raises his crests, and parades toward the female.
|
|
Species within these genera exhibit both sexual and asexual reproduction, high heteriozygosity, ploidies from 2x to 6x, and gene flow between bordering populations as evidence of ongoing introgression. However, this gene flow is only made possible in the presence of B. intermedia, which introgression moves towards, and the absence of which keeps the other species reproductively isolated. B. intermedia is identified as the compilospecies in this model.
|
|
DNA from ancient dogs and wolves suggest that dogs were almost entirely reproductively isolated from wolves in both the Americas and Europe for more than 10,000 years, although limited gene flow has likely occurred in specific lineages, such as in arctic dogs. Wolves have maintained their phenotype differences from the dog, which indicates low-frequency hybridization. There was almost no admixture detected in the North American specimens.
|
|
The dense foliage of Christmas berry shades out native seedlings of the understory by decreasing the amount of light reaching the forest floor by as much as 70%. Its prolific berry yield furthers its ability to form monocultures, as other natives are unable to compete reproductively with the yearlong persistence of berries. These monocultures can reach numbers of over 100 plants per square meter.Kitajima, Kaoru.
|
|
The female has a low fertility rate, and generally produces two litters each year, with two to six (averaging 4.2) young, during the breeding season from spring to summer. The offspring are not reproductively active in their birth summer. Throughout much of the summer after their birth, the young live with their parents and forage on vegetation stored by them. During the following winter most juveniles live with their parents.
|
|
In captivity, bilbies typically live for at least six years with some specimens reaching ten years of age. However, wild caught bilbies tend to be less than 12 months old. Females become reproductively active at six months of age and can breed all year round if conditions are favourable. Greater bilbies have a very short gestation period of about 12–14 days, one of the shortest among mammals.
|
|
Sympatric speciation events are quite common in plants, which are prone to acquiring multiple homologous sets of chromosomes, resulting in polyploidy. The polyploid offspring occupy the same environment as the parent plants (hence sympatry), but are reproductively isolated. A number of models have been proposed for alternative modes of sympatric speciation. The most popular, which invokes the disruptive selection model, was first put forward by John Maynard Smith in 1966.
|
|
Social monogamy has also been observed in reptiles, fish, and insects. Sexual monogamy is defined as an exclusive sexual relationship between a female and a male based on observations of sexual interactions. However, scientific analyses can test for paternity, for example by DNA paternity testing or by fluorescent pigment powder tracing of females to track physical contact. This type of analysis can uncover reproductively successful sexual pairings or physical contact.
|
|
Their social organization is unique among primates and is called a "cooperative polyandrous group". This communal breeding system involves groups of multiple males and females, but only one female is reproductively active. Females mate with more than one male and each shares the responsibility of carrying the offspring. They are the only primate group that regularly produces twins, which constitute over 80% of births in species that have been studied.
|
|
In brewers' yeast Saccharomyces cerevisiae, chromosomal rearrangements are a major mechanism to reproductively isolate different strains. Hou et al. showed that reproductive isolation acts postzygotically and could be attributed to chromosomal rearrangements. These authors crossed 60 natural isolates sampled from diverse niches with the reference strain S288c and identified 16 cases of reproductive isolation with reduced offspring viabilities, and identified reciprocal chromosomal translocations in a large fraction of isolates.
|
|
Nematomorphs possess an external cuticle without cilia. Internally, they have only longitudinal muscle and a non-functional gut, with no excretory, respiratory or circulatory systems. The nervous system consists of a nerve ring near the anterior end of the animal, and a ventral nerve cord running along the body. Reproductively, they have two distinct sexes, with the internal fertilization of eggs that are then laid in gelatinous strings.
|
|
Subordinate females (beta, gamma, or delta) may produce unfertilized eggs but these are usually consumed by the alpha female in a form of "queen policing". Males are born throughout most of the year in tropical species, however Dinoponera australis which lives in the more temperate south was found to only produce males in May–July. When the alpha declines reproductively or dies, she is replaced by a high-ranking worker.
|
|
Embryos are maintained with only endogenous food supplies for about 3–8 months. Reproduction in the sockeye salmon has to be accomplished with the energy stores brought to the spawning grounds. How the salmon use their energy during migration and spawning affects how successful they will be reproductively; energy used for migration cannot also be used for courtship. If they waste too much energy, they might not be able to spawn.
|
|
In addition to the queen, the workers can lay eggs . Since workers do not mate, all of their eggs are haploid and will develop into drones. There are multiple factors that determine whether a worker bee will become reproductively active. Workers born early in the first brood are more likely to become egg layers due to their increased size and age, which allows more time for ovarian development.
|
|
Individuals of M. griveaudi have been found to leave a Grande Comore cave at sunset. Flying M. griveaudi have mostly been recorded in forests, but this may reflect a lack of survey effort in open areas.Goodman et al., 2010, pp. 130–131 In caves, individuals either group in large groups of more than 50 bats without reproductive activity or in smaller groups of at most five reproductively active bats.
|
|
Prunus caroliniana is a small to medium-sized evergreen tree which grows to about tall, with a spread of about . The leaves are dark green, alternate, shiny, leathery, elliptic to oblanceolate, long, usually with an entire (smooth) margin, but occasionally serrulate (having subtle serrations), and with cuneate bases. Reproductively mature trees have entire margins, whereas immature ones often have subtle serrations. The twigs are red to grayish brown, slender, and glabrous.
|
|
Louis-Marie Bobay and Howard Ochman suggest, based on analysis of the genomes of many types of bacteria, that they can often be grouped "into communities that regularly swap genes", in much the same way that plants and animals can be grouped into reproductively isolated breeding populations. Bacteria may thus form species, analogous to Mayr's biological species concept, consisting of asexually reproducing populations that exchange genes by homologous recombination.
|
|
Breeders have considerably larger testes than helpers, as well as faster- and longer-swimming sperm and a higher percentage of motile sperm compared to helpers. The sperm of large helpers are characteristically similar to those of breeders, but helpers have smaller testes. The small size of the helpers' testes, coupled with the physiological equivalence of their sperm compared to breeder sperm, imply that the helpers are reproductively suppressed.
|
|
A stray dog can become feral when it is forced out of the human environment or when it is co-opted or socially accepted by a nearby feral group. Feralization occurs by the development of a fear response to humans. Feral dogs are not reproductively self-sustaining, suffer from high rates of juvenile mortality, and depend indirectly on humans for their food, their space, and the supply of co-optable individuals.
|
|
There is one reproductively-dominant female in each nest. Becoming the dominant female in a nest requires a takeover from the previous dominant female. This can be done by either a nest mate, usually a daughter, or an outside intruder. In takeover attempts, fighting occurs and the defeated female either remains in the nest as a guard or leaves to attempt to found or take over another nest.
|
|
Females mate multiple times, so sperm competition could be an important aspect of male-male competition for being reproductively successful. Males have a limited number of sperm and allocate it depending on various factors. Male Indian-meal moths ejaculate a greater amount of sperm to females that have mated multiple times previously. This is to ensure a greater chance of success in sperm competition in the females' storage organs.
|
|
The pollination efficiency hypothesis suggests that mast seeding may optimize successful pollination and thus fertilization if all individuals within a population are reproductively synchronized. This hypothesis is especially relevant for wind-pollinated species, which many mast seeding species are. Both hypotheses are based on the assumption that large and variable reproductive effort is more efficient than small, consistent reproductive effort, which ultimately leads to higher fitness for the masting population.
|
|
Excerpts From Report on Custody of the Baby Gorilla. The New York Times. In his report Nadler noted that "the recommendation is based on the judgment that an infant gorilla is more likely to develop into a socially competent and reproductively adequate animal if it is raised in the company of its parents as opposed to being raised with a group of peers."Psychologist sends gorilla home. UPI.
|
|
The SRS encompasses 100 hectares (250 acres) for propagation, research and education, and received its first rhino in 1998. Until recently, the Sanctuary held only one pair of animals, which were not reproductively sound. The SRS is now home to seven animals, including calves born in 2012 and 2016. It is staffed by two full-time Indonesian veterinarians, 11 keepers, several administrative and support staff, and protection units.
|
|
The Pearl River map turtle (Graptemys pearlensis) is a species of emydid turtle native to the southern United States. According to a study done in January 2017, the species G. pearlensis was significantly less abundant in the Pearl River region as compared to G. oculifera and exhibited a smaller number of reproductively mature females. Further, this study highlighted statistical and observational evidence that this species exhibited female-biased, sexual dimorphism.
|
|
They go on to conclude that: > Nevertheless, ring species are more convincing than cases of clinal > isolation for showing that gene flow hampers the evolution of reproductive > isolation. In clinal isolation, one can argue that reproductive isolation > was caused by environmental differences that increase with distance between > populations. One cannot make a similar argument for ring species because the > most reproductively isolated populations occur in the same habitat.
|
|
The reproduction rate of the desert mouse is very high, even when compared with other species in the Pseudomys genus. This allows populations to increase rapidly after periods of suitable rainfall. Females are sexually receptive and fertile in a 7-9 day cycle. The gestation period lasts 27–28 days, with an average litter size of three pups who will themselves become reproductively mature at about ten weeks.
|
|
Reports on seasonal variation in range size have been equivocal. One study found a large variation in male range sizes, from in summer up to in winter. Another found that female bobcats, especially those which were reproductively active, expanded their home range in winter, but that males merely shifted their range without expanding it, which was consistent with numerous earlier studies. Other research in various American states has shown little or no seasonal variation.
|
|
The adult worms show territorial behaviour, fighting with other worms of the same species. However the worms are gonochoristic and there must be some mechanism by which a male and female come into close proximity during the period in which they are reproductively active. Some possibilities for this to happen include the hosts being close together, temporary aggregations of individual worms during the breeding season, or by the release of gametes into the sea water.
|
|
Estuary perch breed in winter at the same time as Australian bass, and are similarly sexually dimorphic, with females larger than males. Females reach sexual maturity at older ages and larger sizes than males. In Victoria, estuary perch/Australian bass hybrids are regularly recorded; most hybrids appear to be reproductively viable. Spawning occurs at the mouths of estuaries, rivers, and streams during winter and spring when water temperatures are 14-19 °C.
|
|
Sorbus minima, commonly known as the lesser whitebeam or least whitebeam, is a shrub belonging to the subgenus Aria (whitebeams) in the genus Sorbus. It is endemic to Wales where it grows at a few sites in Breconshire. It is an apomictic microspecies which reproduces asexually and so is reproductively isolated from its close relatives such as the Swedish whitebeam, S. intermedia. It probably originated as a hybrid between the rock whitebeam (S.
|
|
The northern crested newt sometimes hybridises with other crested newt species where their ranges meet, but overall, the different species are reproductively isolated. In a case study in the Netherlands, genes of the introduced Italian crested newt (T. carnifex) were found to introgress into the gene pool of the native northern crested newt. The closest relative of the northern crested newt, according to molecular phylogenetic analyses, is the Danube crested newt (T. dobrogicus).
|
|
The evolutionary process by which biological populations evolve to become distinct or reproductively isolated as species is called speciation. Charles Darwin was the first to describe the role of natural selection in speciation in his 1859 book The Origin of Species. Speciation depends on a measure of reproductive isolation, a reduced gene flow. This occurs most easily in allopatric speciation, where populations are separated geographically and can diverge gradually as mutations accumulate.
|
|
Additionally, physical attractiveness signals genetic quality for both males and females. Men who preferentially mated with healthy, fertile, and reproductively valuable women would have left more descendants than men who did not. Since men's reproductive value does not decline as steeply with age as does women's, women are not expected to exhibit as strong of a preference for youth in a mate. However, male mate value is partly based upon his ability to acquire resources.
|
|
Species are distinguished by their patterns of setae, grooves, and punctures, and features of the male genitalia, as much as by size as shape. Holcaspis adults are most commonly found in summer (November to March), but some have been trapped over winter, suggesting they live two years or more like other long-lived carabids. Several species have been observed being reproductively active over summer. Female:male sex ratios range from 1:0.8 to 1:3.4.
|
|
Downloaded on 20 May 2010. S. aphelios is one of four different forms of the Ohrid trout complex within the single lake, along with S. balcanicus, S. letnica, and S. lumi. The various trout forms, which have been suggested to be different species, are distinguished by their breeding time and habitat, by which they in practice are thought to be reproductively isolated from each other. Genetic data have not supported their distinction, though.
|
|
Archon apollinus, the false Apollo, is a species of butterfly belonging to the Parnassinae subfamily. The species is found in Central and Eastern Europe and West Asia. They are found in Greece, Turkey, Iraq, Syria, Jordan, Israel and Lebanon, and like others of the family show considerable variation with four or five subspecies. A morphologically similar species Archon apollinaris has been recently separated and has been found to be sympatric and reproductively isolated.
|
|
Although it hybridises with the house sparrow in a sparsely populated contact zone in the Alps, the contact zone is characterized by relatively abrupt changes in species-specific male plumage, suggesting that partial reproductive isolation based on plumage may also have developed between these two taxa. As a genetically distinct group that is reproductively isolated from the parental species, it must be recognised as a separate species, according to Hermansen and colleagues.
|
|
An orange aquarium variant (himedaka) achieved through selective breeding, photographed from above. Not to be confused with the brightly-colored transgenic aquarium variants Oryzias latipes is a model organism and is extensively used in many areas of biological research, most notably in toxicology. Medaka have a short gestation period, and are reproductively prolific — characteristics that make them easy to rear in the laboratory. They can withstand cold and can be shipped easily.
|
|
The swamp wallaby becomes reproductively fertile between 15–18 months of age, and can breed throughout the year. Gestation is from 33–38 days, leading to a single young. The young is carried in the pouch from 8–9 months, but will continue to suckle until about 15 months. The swamp wallaby exhibits an unusual form of embryonic diapause, differing from other marsupials in having its gestation period longer than its oestrous cycle.
|
|
So It is concluded that inv(Y) has common genetic origin in Gujarati Muslims of South Africa. The origin is traced to Kholvad, a small village near Surat, and some neighbouring villages. It is probably originated through random genetic drift in reproductively isolated community, maintained by strict endogamy based on religious and linguistic affiliations. ;Vitiligo in Gujaratis Vitiligo is a long term skin condition characterized by patches of the skin losing their pigment.
|
|
However, in 2007, Brian Keener and Larry Davenport published a treatment of the fertile individuals as a distinct species, which they named A. tutwilerae for the original discoverer. They argued that as a fertile, reproductively isolated population sharing a common origin, the fertile individuals were consistent with several popular biological species concepts, and warranted recognition as a species. The segregation of A. tutwilerae from A. × ebenoides made it one of the rarest fern species worldwide.
|
|
Female blue king crabs in the Pribilof Islands grow to the largest size before they are reproductively mature. About 50% of crabs are mature at CL. St. Matthew Island females can become sexually mature at CL and Diomede crabs are similar. Larger female crabs from the Pribilof Islands have the highest fecundity, producing 162,360 eggs or 110,033 larvae per crab. The reduction in fecundity is about 33% between the egg and larval stages.
|
|
Ctenotus pantherinus, commonly known as the leopard ctenotus, is a species of skink endemic to central and western Australia. Ctenotus Pantherinus is commonly known to reproductively be the only species (within the Ctenotus genus) to have a female be smaller in size in comparison to their male counterparts. This has allowed them to both adequately adapt to their environment, as well as, caused them to sustain their population growth.Gordon, C. E., et al.
|
|
A young Cape mountain zebra foal Breeding occurs throughout the year with birth peaks in December to February (summer), and a gestation period of 1 year. A single new-born weighs 25 kg, and are weaned off after 10 months. Bachelor males reach sexual maturity at 5– 6 years when they are capable of becoming herd stallions, while mares produce their first foals at 3–6 years and can remain reproductively active until around 24 years of age.
|
|
Rockhopper penguin skeleton in Manchester Museum It breeds in colonies in a range of locations from sea level or on cliff sides, to sometimes inland. The Northern form, found in Amsterdam and Gough island, is reproductively isolated from the Crozet and Kerguelen islands. They are monophyletic; meaning they have a split in the mitochondria DNA trees which forms two subspecies: the northern and southern rockhopper penguin. Another interesting difference between the two subspecies is their mating ritual.
|
|
There are three extant kinds of mammals: monotremes, placentals and marsupials, all with internal fertilization. In placental mammals, offspring are born as juveniles: complete animals with the sex organs present although not reproductively functional. After several months or years, depending on the species, the sex organs develop further to maturity and the animal becomes sexually mature. Most female mammals are only fertile during certain periods during their estrous cycle, at which point they are ready to mate.
|
|
Dwarf mongooses show synchronous estrous but only the dominant female regularly gives birth. Subordinate females do not conceive or abort early, but do lactate after the dominant female gives birth and participate in communal nursing. When the subordinate females leave the parental pack they will become fully reproductively active in new groups they help establish. In captivity, more than one dwarf mongoose in a group can give birth but the young of subordinates do not survive.
|
|
The strength of natural selection in the wild was greater than expected; the effect of ecological factors such as niche occupation and the significance of barriers to gene flow are all important. The idea that speciation occurs after populations are reproductively isolated has been much debated. In plants, polyploidy must be included in any view of speciation. Formulations such as 'evolution consists primarily of changes in the frequencies of alleles between one generation and another' were proposed rather later.
|
|
An example of the ecological or habitat differences that impede the meeting of potential pairs occurs in two fish species of the family Gasterosteidae (sticklebacks). One species lives all year round in fresh water, mainly in small streams. The other species lives in the sea during winter, but in spring and summer individuals migrate to river estuaries to reproduce. The members of the two populations are reproductively isolated due to their adaptations to distinct salt concentrations.
|
|
Cephalopods that are sexually mature and of adult size begin spawning and reproducing. After the transfer of genetic material to the following generation, the adult cephalopods then die. Sexual maturation in male and female cephalopods can be observed internally by the enlargement of gonads and accessory glands. Mating would be a poor indicator of sexual maturation in females; they can receive sperm when not fully reproductively mature and store them until they are ready to fertilize the eggs.
|
|
The sharks conceal their heads amongst the egg masses, while their stripes break up the outlines of their bodies. As the female squid descend to the sea floor to attach their eggs, guarded by the males, they become vulnerable to the sharks' ambush attacks. Female pyjama sharks lay dark brown egg capsules, which are attached to structures on the sea floor. An oviparous species, both male and female pyjama sharks seem to be reproductively active throughout the year.
|
|
Although mature eucalyptus trees may be towering and fully leafed, their shade is characteristically patchy because the leaves usually hang downwards. The leaves on a mature eucalyptus plant are commonly lanceolate, petiolate, apparently alternate and waxy or glossy green. In contrast, the leaves of seedlings are often opposite, sessile and glaucous, but many exceptions to this pattern exist. Many species such as E. melanophloia and E. setosa retain the juvenile leaf form even when the plant is reproductively mature.
|
|
The most common type of competition in Indian-meal moths is due to a lack of food. This competition can change the timing of male and female emergence, reducing the chance of early males finding females to mate with, which could encourage emigration. This is considered a form of male-male competition because males that emerge at an appropriate time are more likely to be reproductively successful with the surrounding females. Males are also involved in finding pupation sites.
|
|
Species concepts are the subject of debate in the field of molecular ecology. Since the beginning of taxonomy, scientists have wanted to standardize and perfect the way species are defined. There are many species concepts that dictate how ecologists determine a good species. The most commonly used concept is the biological species concept which defines a species as groups of actually or potentially interbreeding natural populations, which are reproductively isolated from other such groups (Mayr, 1942).
|
|
The species is sexually dimorphic in that the female does not have such prominent bone fangs. It becomes sexually mature while its body is still not fully developed; scientists speculate that this may happen because younger fish were more successful reproductively. Ichthyologist Dr Ralf Britz, who named the fish after Bram Stoker's character Count Dracula, stated that the dracula fish "is one of the most extraordinary vertebrates discovered in the last few decades."Devlin, Kate (2009-03-11).
|
|
Sexually mature females were found between fork lengths of with half of them sexually mature at a fork length of . The maless were larger than females and their fork lengths were . These differ from site to site although the sex ratios were the same between sites, with roughly 5.5 females for every male. Off Western Australia the majority of the females were reproductively active between July and December coinciding relatively cool water temperatures and increasing daylight hours.
|
|
While D. albomicans and Drosophila nasuta are commonly referred to as distinct species, there appears to be little to no sexual isolation between these two Drosophila species. Instead, behavioural differences appear to reproductively isolate these two species. The Immigrans species group (to which D. albomicans belongs) is related to the Drosophila quinaria and Drosophila testacea species groups. The related species Drosophila immigrans has been used in evolutionary studies to understand how viruses evolve with their hosts.
|
|
759308 The later and more limited concept is that of a species that has arrived in a specific geographic area from a different region, but its population is not self-sustaining. Population numbers are only increased through re-introduction. After some time, an adventive species may become naturalized; or, some populations do not sustain themselves reproductively, but exist because of continued influx from elsewhere. Such a non-sustaining population, or the individuals within it, are said to be adventive.
|
|
Blesmols live in elaborate burrow systems and different species exhibit varying degrees of sociality. Most species are solitary, but two species, the damaraland blesmol (Fukomys damarensis) and the naked mole-rat (Heterocephalus glaber) are considered to be the only two eusocial mammals. These species are characterized by having a single reproductively active male and female in a colony where the remaining animals are sterile. These animals prefer loose, sandy soils and are often associated with arid habitats.
|
|
The Reserve is one of only four to six reproductively viable populations of the Southwestern pond turtle in southern California.Pires, Marcelo. "An Overview of the Status of the Southwestern Pond Turtle (Clemmys marmorata pallida) in Southern California." Snakes found on the Ecological Reserve include: San Bernardino ring-necked snake, Hammond's two-striped garter snake, coastal rosy boa, Western yellow-bellied racer, California striped racer, San Joaquin coachwhip, red diamond rattlesnake, Southern Pacific rattlesnake, San Diego gopher snake, California kingsnake.Unattributed.
|
|
Ferox trout (Salmo ferox) is a variety of trout found in oligotrophic lakes/lochs of Ireland, England, Scotland and Wales. Ferox trout is a traditional name for large, piscivorous trout, which in Scotland feed largely on Arctic char. It has been argued to be a distinct species, being reproductively isolated from "normal" brown trout (Salmo trutta) of the same lakes, particularly in Ireland. However, it is uncertain whether the ferox of different lakes are all of a single origin.
|
|
A new gamergate often originates from a younger cohort. For example, when the original founding queen dies in a Harpegnathos saltator colony, younger workers begin to fight for dominance and some become the next reproductives. Because reproductively inactive workers are able to activate their ovaries after the death of the gamergate, some gamergate species can be considered cooperative breeders rather than truly eusocial insects. In colonies with both queens and gamergates, the latter function as secondary reproductives.
|
|
Environmental Assessment for AquAdvantage Salmon In November 2015, the FDA of the USA approved the AquAdvantage salmon for commercial production, sale and consumption, the first non-plant GMO food to be commercialised. AquaBounty say that to prevent the genetically modified fish inadvertently breeding with wild salmon, all the fish will be female and reproductively sterile, although a small percentage of the females may remain fertile. Some opponents of the GM salmon have dubbed it the "Frankenfish".
|
|
A brief version of the female default paradigm can be stated as follows: #A set of specific genetic instructions must be present and a series of differentiating events mediated by hormones must occur in order for a mammalian zygote to become a fully reproductively functional male. ##The Y chromosome, SRY, SOX9, and SF1 genes must be present and functional. ##Functional Leydig cells must form in the gonads. ##The Leydig cells must be able to produce testosterone.
|
|
The concept of a hybrid is interpreted differently in animal and plant breeding, where there is interest in the individual parentage. In genetics, attention is focused on the numbers of chromosomes. In taxonomy, a key question is how closely related the parent species are. Species are reproductively isolated by strong barriers to hybridisation, which include genetic and morphological differences, differing times of fertility, mating behaviors and cues, and physiological rejection of sperm cells or the developing embryo.
|
|
Formica polyctena like many ant, wasp and bee species, displays a eusocial system. Eusocial insects are characterized by cooperative care of young among members of a colony, distinct caste systems where some individuals breed and most individuals are sterile helpers, and overlapping generations so mother, adult offspring and immature offspring are all living at the same time. In a eusocial colony, an individual is assigned a specialized caste before they become reproductively mature, which makes them behaviorally distinct from other castes.Davies, pg.
|
|
It was therefore surmised that an Octomys-like ancestor produced tetraploid (i.e., 2n = 4x = 112) offspring that were, by virtue of their doubled chromosomes, reproductively isolated from their parents. Polyploidy was induced in fish by Har Swarup (1956) using a cold-shock treatment of the eggs close to the time of fertilization, which produced triploid embryos that successfully matured. Cold or heat shock has also been shown to result in unreduced amphibian gametes, though this occurs more commonly in eggs than in sperm.
|
|
While few animals urinate through the clitoris or use it reproductively, the spotted hyena, which has an especially large clitoris, urinates, mates, and gives birth via the organ. Some other mammals, such as lemurs and spider monkeys, also have a large clitoris. The clitoris is the human female's most sensitive erogenous zone and generally the primary anatomical source of human female sexual pleasure. In humans and other mammals, it develops from an outgrowth in the embryo called the genital tubercle.
|
|
Increasing body weight is also thought to be linked to the development of polycystic ovary syndrome (PCOS). PCOS is a very common endocrine disorder among women who are reproductively active with a prevalence of 5-10%. Many women who have PCOS are also obese, and it is estimated that the prevalence of obesity in women with PCOS is 35 - 63%. PCOS diagnosis is defined by the Rotterdam criteria of having at least two of the following: polycystic ovaries, hyperandrogenism, and ovulatory dysfunction.
|
|
Bacteriocyte tissue grows considerably during nymphal and larval development as it organizes into two regular clusters near the gut and developing embryonic chains. As some insects grow older, such as aphids, they begin to exhibit disorganized architecture in the bacteriocyte tissue. Eventually, this trend leads to progressive dis-aggregation of the tissue caused by an increasing lack of intercellular adhesion of the cells that only increases as the insect ages. Dis-aggregation appears prominently in reproductively active as well as senescent adults.
|
|
By the end of the summer, mature larvae leave the nuts by round holes then burrow into the ground where they build individual cells. After overwintering, most larvae diapause for the whole season and undergo metamorphosis in the next summer. Newly formed adults then mainly overwinter in their pupal cases before emerging in the spring of the following year. Adult females are reproductively immature at emergence and ovarian development is only attained from 1 to 2 months later, after the feeding period.
|
|
The sister species Drosophila subquinaria and Drosophila recens overlap in geographic range and are capable of hybridization, meaning they can successfully reproduce with each other; however the offspring are very sickly. Thus, these two species are almost fully reproductively isolated, despite overlapping in geographic range. One reason for this is behavioural, driven by pheromones. D. subquinaria females readily avoid mating with males from other species, but surprisingly D. subquinaria females also avoid mating with males from the same species in allopatric populations.
|
|
Juvenile gray langur Tufted gray langur with young Gray langur with newborn In one-male groups, the resident male is usually the sole breeder of the females and sires all the young. In multiple-male groups, the highest-ranking male fathers most of the offspring, followed by the next-ranking males and even outside males will father young. Higher-ranking females are more reproductively successful than lower-ranking ones. Female gray langurs do not make it obvious that they are in estrous.
|
|
Notitia Occidens XLII Reproductively self-sufficient groups of laeti (i.e. including women and children) would be granted land (terrae laeticae) to settle in the empire by the imperial government. They appear to have formed distinct military cantons, which probably were outside the normal provincial administration, since the settlements were under the control of a Roman praefectus laetorum (or praefectus gentilium), who were probably military officers, as they reported to the magister peditum praesentalis (commander of the imperial escort army) in Italy.Notitia Occ.
|
|
Asian black bears are reproductively compatible with several other bear species, and have on occasion produced hybrid offspring. According to Jack Hanna's Monkeys on the Interstate, a bear captured in Sanford, Florida, was thought to have been the offspring of an escaped female Asian black bear and a male American black bear, and Scherren's Some notes on hybrid bears published in 1907 mentioned a successful mating between an Asian black bear and a sloth bear.Hybrid Bears. Messybeast.com. Retrieved on 2011-09-26.
|
|
The Nassau grouper is fished both commercially and for sport; it is less shy than other groupers, and is readily approached by scuba divers. However, its numbers have been sharply reduced by overfishing in recent years, and it is a slow breeder. Furthermore, its historic spawning areas are easily targeted for fishing, which tends to remove the reproductively active members of the group. The species is therefore highly vulnerable to overexploitation, and is recognised as critically endangered on the IUCN Red List.
|
|
Species tend to flower at a specific time of day as well, with these periods being well defined enough to presumably isolate different species reproductively. Furthermore, some species exhibit differential opening times for male and bisexual flowers. Commelinaceae flowers tend to deceive pollinators by appearing to offer a larger reward than is actually present. This is accomplished with various adaptations such as yellow hairs or broad anther connectives that mimic pollen, or staminodes that lack pollen but appear like fertile stamens.
|
|
According to Lamarck's long- discredited theory of evolution, anatomy will be structured according to functions associated with use; for instance, giraffes are taller to reach the leaves of trees. By contrast, in Darwinian evolution, form (variation) precedes function (as determined by selection). This is to say, in Lamarckian evolution the form is altered by the required function, whereas in Darwinian evolution small variations in form allow some parts of the population to function better, and are therefore more successful reproductively.
|
|
Bombus bohemicus, also known as the gypsy's cuckoo bumblebee, is a species of socially parasitic cuckoo bumblebee found in most of Europe with the exception of the southern Iberian Peninsula and Iceland. B. bohemicus practices inquilinism, or brood parasitism, of other bumblebee species. B. bohemicus is a generalist parasite, successfully invading several species from genus Bombus. The invading queen mimics the host nest's chemical signals, allowing her to assume a reproductively dominant role as well as manipulation of host worker fertility and behavior.
|
|
The queen produces a combination of chemicals that mimic the fertility signals of the host queen, specifically wax-type esters, tetracosyl oleate, and hexacosyl oleate. These chemical signals are transferred to nearby workers via physical contact in the form of non-aggressive body rubbing. These signals mimic those of reproductively active host queens, suppressing ovarian development of the host workers. No significant difference has been found between worker reproductive suppression by native queens and invading queens, illustrating the effectiveness of the chemical mimicry.
|
|
This loss of dominance is likely tied to the loss of dominance by the host queen in cases where she survived invasion and remained in the nest, though the nature of this association is not understood. This loss of dominance is characterized by the maturation of worker ovaries as they become reproductively active. The invasive queen is not necessarily killed after dominance is lost, but may remain in the hive, either incubating host cocoons or sitting inactively beside the comb.
|
|
The classic work carried out by Andrew Ferguson of Queens University on the genetics of the trout of Lough Melvin identified the ferox as a separate subspecies. The fish home to a specific spawning area and are reproductively isolated. They are also one of the oldest trout races to colonise Ireland, perhaps as old as 50,000 years. Ferox cannibalise brown trout (which returned to many of the same lakes when geological processes and climatic conditions allowed) and also prey on other fish species.
|
|
Average weekly adult survival rate of eastern towhees in a South Carolina study area was 99.3%. This rate was obtained from radio-marked eastern towhees and represented the pooled survival of both sexes and from 2 South Carolina sites, young and mature stands of loblolly and longleaf pine. Between 1962 and 1967 in Pennsylvania, annual survival of breeding eastern towhees calculated from mistnetting recaptures was 58%. According to a literature review, both males and females become reproductively mature in their second year.
|
|
The Ethiopian wolf is a social animal, living in family groups containing up to 20 adults (individuals older than one year), though packs of six wolves are more common. Packs are formed by dispersing males and a few females, which with the exception of the breeding female, are reproductively suppressed. Each pack has a well-established hierarchy, with dominance and subordination displays being common. Upon dying, a breeding female can be replaced by a resident daughter, though this increases the risk of inbreeding.
|
|
However, during the adaptation to reproductively inhibitory photoperiods, the levels of T3 decrease due to peri-hypothalamic DIO3 expression that catabolizes T4 and T3 into receptor inactive amines . Deiodinase 2 also plays a significant role in thermogenesis in brown adipose tissue (BAT). In response to sympathetic stimulation, dropping temperature, or overfeeding BAT, D2 increases oxidation of fatty acids and uncouples oxidative phosphorylation via uncoupling protein, causing mitochondrial heat production. D2 increases during cold stress in BAT and increases intracellular T3 levels.
|
|
Hybrids may also form novel lineages that are reproductively isolated from both parent taxa. The coloured fractions of the bars in the bar plots below show the relative proportion of the genome belonging to the blue and green parental lineages respectively. The grey bars represent a speciation reversal where differences are selected against. Finally, if hybridization leads to unfit offspring, it may reduce the fitness of the involved parental taxa due to wasted reproductive effort and may increase extinction risks for these.
|
|
L. janetae has 8 gonads which are shaped like lances and arranged in pairs extending from the centre of the calyx to the base of the arms. They give the organism an orange/pink colour when reproductively active. The scientists who originally identified L. janetae have speculated that this species may also be capable of asexual reproduction. This had not been shown for any Stauromedusan at the time the paper was written, although it has subsequently been suggested for Haliclystus antarcticus.
|
|
Predator-induced polyphenisms allow the species to develop in a more reproductively-successful way in a predator's absence, but to otherwise assume a more defensible morphology. However, this can fail if the predator evolves to stop producing the kairomone to which the prey responds. For example, the fly larvae that feed on Daphnia cucullata (a water flea) release a kairomone that Daphnia can detect. When the fly larvae are present, Daphnia grow large helmets that protect them from being eaten.
|
|
These acaricides target primarily the adult stages of Lyme- carrying ticks and reduce the number of reproductively active ticks in the environment. Formulations of these ingredients are available in a variety of topical forms, including spot-ons, sprays, powders, impregnated collars, solutions, and shampoos. Examination of a dog for ticks after being in a tick- infested area is an important precautionary measure to take in the prevention of Lyme disease. Key spots to examine include the head, neck, and ears.
|
|
Greenside darters typically live for three to five years, grow to a maximum of 132 mm standard length and sexually mature at one to two years of age. Greenside darters are reproductively active from February to April in the Midwest and Southeastern United States. Spawning occurs over algae- or moss- covered rocks in deep, swift riffles that are guarded by males that vigorously defended against intruders. Females linger in pools below the riffle and move into a male's territory when ready to spawn.
|
|
The opposite is not true; disruption of normal sexual development in females does not lead to male-typical endpoints. Defeminization involves the suppression of the development of female typical morphology (development of the Müllerian ducts into the fallopian tubes, uterus and vagina) and behavioural predispositions. Masculinization involves the production of male typical morphology (development of the Wolffian ducts into male reproductive structures) and behavioural predispositions. Both defeminization and masculinization are required for a mammalian zygote to become a fully reproductively functional male.
|
|
Breeding occurs between June and August when the females come into estrus. All male brush-tailed phascogales die before reaching one year of age, generally from stress-related diseases brought about by the energy expended in a bout of frenzied mating. However, some captive males have lived to the age of three, though they were reproductively unviable after the first year. Females nest in hollow trees, bearing litters of 7 to 8 young which stay in the nest to the age of 5 months.
|
|
As its relatives, this parrotfish starts as female and then changes to male (known as the terminal phase). However, unlike most of its relatives, it is a secondary gonochorist. This means that some females do not change sex (they remain females throughout their lives), the ones that do change from female to male do it while still immature (reproductively functioning females do not change to males) and there are no males with female-like colours (known as initial phase males in other parrotfish).Sadovy & Shapiro (1987).
|
|
In 2000, the U.S. Fish and Wildlife Service initiated a silvery minnow egg salvage pilot project. Biologists from the Service, Bureau of Reclamation, and University of New Mexico collect minnow eggs as well as reproductively-ready adult minnows near Elephant Butte, where these efforts do not disturb upstream populations. Captured adult minnows are induced to spawn, either at the Albuquerque Biological Park or the Service's New Mexico Fishery Resources Office. Biologists then either return the resulting fish to the Rio Grande or hold them for captive propagation.
|
|
An older female watches over pups while alpha female is away. Meerkats become reproductively active at one year of age and can have up to four litters per year. However, usually it is the alpha pair that reserves the right to mate and will usually kill any young that is not their own. While the alpha female is away from the group, females that have never reproduced lactate and hunt in order to feed the pups, as well as watch, protect, and defend them from predators.
|
|
The nest is then joined by a newly mated queen, at which point many workers take up permanent residence and help the new queen raise her own workers. If a ruling queen is herself weak or dying, then a new queen can replace her. For Plebeia quadripunctata, although fewer than 1% of female worker cells produce dwarf queens, they comprise six of seven queen bees, and one of five proceed to head colonies of their own. They are reproductively active, but less fecund than large queens.
|
|
A. swainsonii and A. minimums occur in Tasmania and their reliance on the rate of change of the photoperiod for reproduction is less certain. This is because in higher latitudes the photoperiod changes much faster. Animals that mate when the photoperiod is changing by 35-90s/day would only have 2–3 days in Tasmania compared with 2 weeks in New South Wales. Females control the synchrony of mating, with males reproductively mature and ready to mate 4–5 weeks before the breeding season.
|
|
Naturalists introduced the biological species concept, the definition of species as a community that is reproductively isolated and occupies a distinctive ecological niche. They also recognized that species are polytypic, having variations in time and space; and that behavior and change of function can give rise to evolutionary change. The two groups used such different methods and terminology that it was difficult for them to communicate. They were often battling over the same scarce academic resources, and each was often scornful of the other.
|
|
Sternarchogiton nattereri is a species of weakly electric knifefish in the family Apteronotidae. It is native to the Amazon River system and feeds on sponges. Unlike other members of the genus Sternarchogiton, there is pronounced sexual dimorphism in S. nattereri, with reproductively mature males developing strong external teeth on tips of their jaws. These males are so different from the females and juveniles that they were thought to be a different genus and species, the "tooth-lip knifefish" Oedemognathus exodon, for over 40 years.
|
|
Studies have shown that the number of flowers of an unrewarding morph type that are sampled depends on the frequency of those morphs within a population. For example, many species of obligately animal-pollinated, deceptive orchids that co-occur with rewarding flowers are only reproductively successful when they occur at low frequencies. It is worth mentioning that these two hypotheses are not mutually exclusive in that morph populations that are visited by naive pollinators are also likely to be found at low frequencies relative to rewarding morphs.
|
|
Salmo balcanicus is a type of trout, a fish in the family Salmonidae. It is endemic to Lake Ohrid and its outlet in North Macedonia and Albania in the Balkans. Salmo balcanicus is one of four different forms of the Ohrid trout complex which is endemic to the single lake, along with Salmo letnica, Salmo aphelios and Salmo lumi. The various forms, suggested to be different species, are distinguished by their breeding time and habitat, by which they in practice are reproductively isolated from each other.
|
|
A dog can become a stray when it escapes human control, by abandonment or being born to a stray mother. A stray dog can become feral when forced out of the human environment or when co-opted or socially accepted by a nearby feral group. Feralization occurs through the development of a fear response to humans. Feral dogs are not reproductively self-sustaining, suffer from high rates of juvenile mortality, and depend indirectly on humans for their food, their space, and the supply of co-optable individuals.
|
|
The earliest ribosomal gene sequence data indicated that Symbiodinium had lineages whose genetic divergence was similar to that seen in other dinoflagellates from different genera, families, and even orders. This large phylogenetic disparity among clades A, B, C, etc. was confirmed by analyses of the sequences of the mitochondrial gene coding for cytochrome c oxidase subunit I among Dinophyceae. Most of these clade groupings comprise numerous reproductively isolated, genetically distinct lineages (see ‘Species diversity’), exhibiting different ecological and biogeographic distributions (see ‘Geographic distributions and patterns of ‘diversity’).
|
|
From genetic and mating call analysis and, researchers were able to identify that two populations of the túngara frog were almost completely reproductively isolated. From their research, scientists believe that differences in female preferences for mating call type have led to the evolution of this speciation process. Specifically, the Yasuní population females prefer the male mating call that includes a whine, while the other population does not prefer this whine. Subsequently, the Yasuní males include the whine in their call, while the other males do not.
|
|
When the male emerges from hibernation it starts feeding and is immediately reproductively active. Once the female emerges, which is only a short time after the males, they begin mating, and only about two weeks after emergence all the females are pregnant and gestation begins. Gestation lasts about eighteen days, although this can be a bit longer if the female is still nursing her previous litter. The average litter size is said to be 5.3 young, but can range anywhere from two to nine young.
|
|
Females that eclose later tend to become foragers and will have higher mortality rates than reproductive females. First eclosed females take on a guarding role, which increases their risk of danger in from predators and competitors at the nest entrance. However, the increased risk of guarding pays the reproductively dominant females because it allows them to regulate the reproduction of their nestmates. Dominants are much less likely to allow a female to return into the nest after she has interacted with a foreign male.
|
|
In the Kaneshiro model, a sample of a larger population results in an isolated population with less males containing attractive traits. Over time, choosy females are selected against as the population increases. Sexual selection drives new traits to arise (green), reproductively isolating the new population from the old one (blue). When a sexual species experiences a population bottleneck—that is, when the genetic variation is reduced due to small population size—mating discrimination among females may be altered by the decrease in courtship behaviors of males.
|
|
Poecilia parae are known to have a number of colour morphs in the males, at least five distinct morphs are known, while there is a single female colour form. The colour of the male is linked to the Y-chromosome. Some of the morphs are always abundant in the wild, and others are invariably rare leading to the conclusion that the colour of the males has implications for their fitness. Laboratory work has shown that the most frequent morph is also the most reproductively successful morph.
|
|
Forensic reconstruction of an adult male Homo erectus.Reconstruction by W. Schnaubelt & N. Kieser (Atelier Wild Life Art), 2006, Westfälisches Museum für Archäologie, Herne, Germany. Map of the distribution of Middle Pleistocene (Acheulean) cleaver finds It has been proposed that H. erectus evolved from H. habilis about 2 Mya, though this has been called into question because they coexisted for at least a half a million years. Alternatively, a group of H. habilis may have been reproductively isolated, and only this group developed into H. erectus (cladogenesis).
|
|
King threadfin occur in shallow, turbid waters such as coastal waters, estuaries, mangrove creeks, and mangrove-lined rivers, over sandbanks and mud substrates. It normally aggregates into loose schools, however, the larger individuals are more frequently recorded as pairs or as individuals. This is a carnivorous species which feeds on prawns and fish. It is a protandrous hermaphrodite and fish between fork lengths of appear to be transitional hermaphrodites in that they have mature male and immature female reproductive organs, and they function reproductively as males.
|
|
The botanists G. Ledyard Stebbins and Verne Grant were two of the well known botanists who championed the idea of hybrid speciation during the 1950s to the 1980s. Hybrid speciation, also called polyploid speciation (or polyploidy) is speciation that results by an increase in the number of sets of chromosomes. It is effectively a form of sympatric speciation that happens instantly. Grant coined the term recombinational speciation in 1981; a special form of hybrid speciation where a new species results from hybridization and is itself, reproductively isolated from both its parents.
|
|
The concept of the ecological niche has been used in a number of ways in anthropology: as a specialized part of human society, as synonymous with culture, and as a segment of the habitat (Donald 1972). Indian society is an agglomeration of several thousand endogamous groups or castes each with a restricted geographical range and a hereditarily determine mode of subsistence. These reproductively isolated castes may be compared to biological species, and the society thought of as a biological community with each caste having its specific ecological niche (Gadgil and Malhotra 1983).
|
|
Ten simulations of random genetic drift of a single given allele with an initial frequency distribution 0.5 measured over the course of 50 generations, repeated in three reproductively synchronous populations of different sizes. In general, alleles drift to loss or fixation (frequency of 0.0 or 1.0) significantly faster in smaller populations. Genetic drift is the change in the relative frequency in which a gene variant (allele) occurs in a population due to random sampling. That is, the alleles in the offspring in the population are a random sample of those in the parents.
|
|
In 2009, it was reported that a genetic change in some members of this species caused their colouration and songs to be different from other members of the species. As a result, members in one group did not recognize members in the other, so the two groups became reproductively isolated from each other. It was thought that over time, this could eventually lead to the creation of a new species, and that this was an example of biological evolution.Beautiful plumage: Feather color and sex start the species revolution, eurekalert.
|
|
The nematode excysts in the intestine, feeds, grows, mates, and releases eggs into the seawater in the host's feces. As the gut of a marine mammal is functionally very similar to that of a human, Anisakis species are able to infect humans who eat raw or undercooked fish. The known diversity of the genus has increased greatly since mid-1980s with the advent of modern genetic techniques in species identification. Each final host species was discovered to have its own biochemically and genetically identifiable "sibling species" of Anisakis, which is reproductively isolated.
|
|
For adult women who are obese and are reproductively active, each unit increase in BMI over a BMI of 32 kg/m2 is associated with a reduction of spontaneous conception rate by 5%. Obesity and overweight among women of reproductive age have been associated with reduced success of conception and a higher risk of complications during pregnancy. Individuals who are obese are at an increased risk of death compared to individuals who are classified as normal weight. This increased risk persists for those who are classified as class 2 and 3 obese.
|
|
Water voles are usually found within 5 to 10 m from waterways. They form a polygynous social group, in which females tend to stay within their territory, which does not overlap other females, and males travel between burrows to reproduce with several females. Because of this system, males travel over a much larger home range than females, and they tend to be more aggressive than females, with aggressiveness coinciding with breeding patterns. Estrus is induced by contact with reproductively active males, and tends to first coincide with the appearance of vegetation in the spring.
|
|
There have been several studies done on the habitat of the vole, given its very specific requirements, to find out if grazing or precipitation levels affect the vole populations so that we can protect them. It has been found that higher precipitation levels create increased availability of usable habitat for water voles. In years of that are wetter than usual it has been observed that young water voles become reproductively active sooner, and therefore can have more offspring. The mean number of pups in each litter increased as well.
|
|
Nectar spurs aid in pollination by making the nectar further from the stamen, ensuring that insect or bird pollinators pick up pollen as they access it. These led rapid speciation within the genus as plants and their pollinators can become specialised to each other i.e. a species of pollinator exclusively feeds from a species of plant, and thus plant populations could easily become reproductively isolated from one another. In addition the shape and size of the nectar spur can evolve in response to pollinator adaptations, developing a co-evolutionary relationship.
|
|
Two species mate resulting in a fit hybrid that is unable to mate with members of its parent species. Hybrid speciation is a form of speciation where hybridization between two different species leads to a new species, reproductively isolated from the parent species. Previously, reproductive isolation between hybrids and their parents was thought to be particularly difficult to achieve, and thus hybrid species were thought to be extremely rare. With DNA analysis becoming more accessible in the 1990s, hybrid speciation has been shown to be a fairly common phenomenon, particularly in plants.
|
|
The Central Valley in California prevents the two salamander populations from interacting with each other which is an example of habitat isolation. After many generations the two salamander gene pools will become mutated caused by natural selection. The mutation will change the DNA sequence of the two populations enough that the salamander populations can no longer successfully breed between each other making the populations of salamander become classified as different species. Any of the factors that prevent potentially fertile individuals from meeting will reproductively isolate the members of distinct species.
|
|
The black-and-white ruffed lemur (Varecia variegata) is an endangered species of ruffed lemur, one of two which are endemic to the island of Madagascar. Despite having a larger range than the red ruffed lemur, it has a much smaller population that is spread out, living in lower population densities and reproductively isolated. It also has less coverage and protection in large national parks than the red ruffed lemur. Three subspecies of black-and-white ruffed lemur have been recognized since the red ruffed lemur was elevated to species status in 2001.
|
|
The only tribe in the family Apidae that do not form large colonies are the Euglossini, because they tend to move independently. Because of this distinction, there are no worker bees or queen bees because there would not be a need for such roles in independent movement. This was proven through the analysis of the number of females in comparison to the number of cells in the hive. Because the number of females outweigh the number of cells, one can assume that there are some female bees who are reproductively inactive.
|
|
Workers are sterile, with the smaller focusing on gathering food and maintaining the nest, while larger workers are more reactive in case of attack. The non-reproducing females appear to be reproductively suppressed, meaning the ovaries do not fully mature, and do not have the same levels of certain hormones as the reproducing females. On the other hand, there is little difference of hormone concentration between reproducing and non-reproducing males. In experiments where the reproductive female was removed or died, one of the non-reproducing females would take over and become sexually active.
|
|
Like S. vulgaris, S. eboracensis is self-compatible; however, it shows little or no natural crossing with its parent species, and is therefore reproductively isolated, indicating that strong breed barriers exist between this new hybrid and its parents. It resulted from a backcrossing of the F1 hybrid of its parents to S. vulgaris. S. vulgaris is native to Britain, while S. squalidus was introduced from Sicily in the early 18th century; therefore, S. eboracensis has speciated from those two species within the last 300 years. Other hybrids descended from the same two parents are known.
|
|
This species is reproductively active particularly in the morning; hence its common name, the morning cicada. It used to be widely known as Tibicen chloromerus, but in 2005 the name was changed to Tibicen tibicen because the species was determined to have been described first under this specific epithet. Likewise, the name of this cicada was changed again in July 2015 due to taxonomic reconfiguration and evaluation of genetics and physiology of the genus Tibicen. The genus Tibicen is now restricted to only a few European cicada species.
|
|
It eats a variety of foods, including insects, exudates, fruits and other plant parts. Insects and fruits account for the majority of its diet, but exudates are also important. But since its teeth are not adapted for gouging trees to get to the sap, it can only eat exudates when they are easily available. Although a variety of reproductive methods are used, the most common is for a single adult female in the group to be reproductively active and to mate with multiple adult males in the group.
|
|
The usual reservoir for coenurosis in man is the dog Coenurosis is a parasitic infection that results when humans ingest the eggs of dog tapeworm species Taenia multiceps, T. serialis, T. brauni, or T. glomerata. It is important to distinguish that there is a very significant difference between intestinal human tapeworm infection and human coenurosis. Humans are the definitive hosts for some tapeworm species, the most common being T. saginata and T. solium (beef and pork tapeworms). This means that these species can develop into full grown, reproductively capable adult worms within the human body.
|
|
Generalized fungus farming in ants appears to have evolved about 55-60 Mya, but early 25 Mya ants seemed to have domesticated a single fungal lineage with gongylidia to feed colonies. This evolution of using gongylidia appears to have developed in the dry habitats of South America, away from the rainforests where fungus-farming evolved. About 10 million years later, leaf-cutting ants likely arose as active herbivores and began industrial-scaled farming. The fungus the ants grew, their cultivars eventually became reproductively isolated and co-evolved with the ants.
|
|
The sterile diploid hybrid of A. montanum and A. platyneuron, which resembles A. bradleyi except for its abortive spores and smaller sori, was not collected until 1972, at Crowder's Mountain, Georgia. Even though the diploid hybrid is rarely collected, allozyme studies show that A. bradleyi has multiple origins; that is, different populations of A. bradleyi have originated from the chromosome doubling of independently formed diploids. Despite their independent origins, these populations are probably interfertile and not reproductively isolated from one another. In addition to its parental species, A. bradleyi hybridizes with several other spleenworts.
|
|
Many of the concepts are quite similar or overlap, so they are not easy to count: the biologist R. L. Mayden recorded about 24 concepts, and the philosopher of science John Wilkins counted 26. Wilkins further grouped the species concepts into seven basic kinds of concepts: (1) agamospecies for asexual organisms (2) biospecies for reproductively isolated sexual organisms (3) ecospecies based on ecological niches (4) evolutionary species based on lineage (5) genetic species based on gene pool (6) morphospecies based on form or phenotype and (7) taxonomic species, a species as determined by a taxonomist.
|
|
Epinephelus albomarginatus is found on rocky and coral reefs at depths between > This is a predatory species which preys largely on spiny lobsters, crab and octopuses, it will also eat fish and squid. These fish grow slowly and they are monandric protogynous hermaphrodites, which means that all of the males are derived from reproductively functional females. Fish sampled along the eastern coast of South Africa are normally sexually immature and this suggests that there may be a northward movement of fish to spawn. Adults remain off northern Kwaulu Natal and southern Mozambique.
|
|
The discoverer, anthropologist Nicholas Conard, said: "This [figure] is about sex, reproduction... [it is] an extremely powerful depiction of the essence of being female". Anthropologist, Paul Mellars of Cambridge University has suggested that—by modern standards—the figurine "could be seen as bordering on the pornographic". Anthropologists from Victoria University of Wellington have suggested that such figurines were not depictions of beauty, but represented "hope for survival and longevity, within well-nourished and reproductively successful communities", reflecting the conventional interpretation of these types of figurines as representing a fertility goddess.
|
|
Oriental trumpeter whiting are reproductively mature at around 130mm in 50% of fish, with the minimum a length of 113mm in males and 109mm in females. They are multiple spawners, that spawn continuously throughout the year with peaks in reproduction that appear to vary geographically. Studies in Thailand indicate the peak is between July and December, while studies in Japan show a peak in February to May. Otolith studies show both females and males attained 60% and 91% of individuals at maturity respectively at the end of their first year of life.
|
|
While most bird species are socially monogamous, molecular data has revealed that less than 25% of these species are genetically monogamous. EPFs complicate matters, especially for male individuals, because it does not make sense for an individual to care for offspring that are not their own. Studies have found that males will adjust their parental care in response to changes in their paternity. Other studies have shown that in socially monogamous species, some individuals will employ an alternative strategy to be reproductively successful since a social bond does not always equal reproductive success.
|
|
Therefore, when a queen only mates once, workers should choose to help rear the offspring of other workers to increase their genetic success. If a queen mates more than once, it is in the worker's best interest to rear the queen's sons. To remedy this worker queen conflict, D. saxonica demonstrates facultative worker policing, where workers inhibit other workers from reproducing – through acts like eating workers’ eggs – so that the queen remains reproductively dominant. This, however, is only in the workers’ best interest if the queen mate multiplied.
|
|
The tadpoles exhibit phenotypic plasticity, with some changing from an omnivorous morphology into a cannibalistic carnivorous morph with oversized jaw muscles and pronged beaks. In some cases, female spadefoot toads will choose to mate with Spea multiplicata rather than with males of their own species, if the resulting hybrid tadpole would have higher chances of survival. Character displacement has also been examined in ponds where Spea bombifrons and Spea multiplicata occur together. Reproductive and ecological competition between the two species likely causes selection for smaller and less reproductively successful individuals of Spea multiplicata.
|
|
Whereas hybridization is required for the generation of persistent hybrid genomes, it is not sufficient. For the persistence of hybrid genomes in hybrid species they need to be sufficiently reproductively isolated from their parent species to avoid species fusion. Selection on introgressed variants allows the persistence of hybrid genomes in introgressed lineages. Frequency of hybridization, viability of hybrids, and the ease at which reproductive isolation against the parent species arises or strength of selection to maintain introgressed regions are hence factors influencing the rate of formation of stable hybrid lineages.
|
|
Hermaphroditism is extremely rare in the insect world despite the comparatively common nature of this condition in the crustaceans. Several species of Icerya, including the pestiferous cottony-cushion scale, Icerya purchasi, are known to be hermaphrodites that reproduce by self- fertilising. Occasionally reproductively functioning males are produced from unfertilised eggs but generally individuals are monoecious and with a female- like nature but possessing an ovotestis which is part testis part ovary and sperm is transmitted ovarially from the female to her young.THE EVOLUTION OF ALTERNATIVE GENETIC SYSTEMS IN INSECTS.
|
|
Possible hybrid grizzly bear-black bear in Yukon Territory, Canada American black bears are reproductively compatible with several other bear species and occasionally produce hybrid offspring. According to Jack Hanna's Monkeys on the Interstate, a bear captured in Sanford, Florida, was thought to have been the offspring of an escaped female Asian black bear and a male American black bear."Hybrid Bears". messybeast.com In 1859, an American black bear and a Eurasian brown bear were bred together in the London Zoological Gardens, but the three cubs that were born died before they reached maturity.
|
|
Only one female and up to three males in the colony reproduce, while the rest of the members are smaller and sterile, and function as workers. Some individuals are of intermediate size. They help with the rearing of the young and can take the place of a reproductive if one dies. The Damaraland mole rat is characterized by having a single reproductively active male and female in a colony where the remaining animals are not truly sterile, but become fertile only if they establish a colony of their own.
|
|
The most common predators of the species include various owls, such as barn owls, short-eared owls, and lesser horned owls. However, various other local predators, including lesser grisons, zorros, and buzzard-eagles, may also include southern big-eared mice in their diets. Southern big-eared mice breed throughout the spring and summer, and typically give birth to litters of four or five young. The young reach independence at a relatively early age, and those born in spring are generally reproductively active before the breeding season finishes in late summer.
|
|
Insect castes: Replete and worker honeypot ants Myrmecocystus mimicus The caste system of insects enables eusociality, the division of labor between non-breeding and breeding individuals. A series of polyphenisms determines whether larvae develop into queens, workers, and, in some cases soldiers. In the case of the ant, P. morrisi, an embryo must develop under certain temperature and photoperiod conditions in order to become a reproductively-active queen. This allows for control of the mating season but, like sex determination, limits the spread of the species into certain climates.
|
|
A colony of vampire bats Male vampire bats guard roosting sites that attract females, but females often switch roosts During estrus, a female releases one egg. Mating usually lasts three to four minutes; the male bat mounts the female from the posterior end, grasps her back with his teeth, holds down her folded wings, and inseminates her. Vampire bats are reproductively active year-round, although the number of conceptions and births peak in the rainy season. Females give birth to one offspring per pregnancy, following a gestation period of about seven months.
|
|
Carbonton Dam, which threatened the shiner's habitat until its destruction in 2005 The Cape Fear shiner is only known from five different populations, two of which are extremely small and run a high risk of extinction. The other three populations are more stable, and are estimated to number between 1500 and 3000 individual fish that are reproductively viable. The Cape Fear shiner was recognized as "Endangered with Critical Habitat" on September 25, 1987 under the Endangered Species Act of 1973. Since 1987, the shiner has dwindled both in range and population.
|
|
Males are reproductively fertile from June to late September, and most mature females are pregnant by the end of July. The females are capable of storing semen in their reproductive tracts for extended periods. Gestation lasts eight weeks, and, in many parts of Africa, birth of one or two young occurs at the beginning of the wet season, around November, although in other areas it can apparently happen at any time of the year. The young are weaned at eight weeks, and are fully grown at five months.
|
|
Both autopolyploid and allopolyploid plants can often reproduce normally, but may be unable to cross-breed successfully with the parent population because there is a mismatch in chromosome numbers. These plants that are reproductively isolated from the parent species but live within the same geographical area, may be sufficiently successful to form a new species. Some otherwise sterile plant polyploids can still reproduce vegetatively or by seed apomixis, forming clonal populations of identical individuals. Durum wheat is a fertile tetraploid allopolyploid, while bread wheat is a fertile hexaploid.
|
|
Florigen is produced in the leaves in reproductively favourable conditions and acts in buds and growing tips to induce a number of different physiological and morphological changes. Once this process begins, in most plants, it cannot be reversed and the stems develop flowers, even if the initial start of the flower formation event was dependent of some environmental cue. Once the process begins, even if that cue is removed the stem will continue to develop a flower. Flower induction and initiation can simply occur when a plant has reached a mature enough age.
|
|
The Fagaceae, or beech family, to which the oaks belong, is a very slow evolving clade compared to other angiosperms, and the patterns of hybridization and introgression in Quercus pose a great challenge to the concept of a species since a species is often defined as a group of "actually or potentially interbreeding populations which are reproductively isolated from other such groups." By this definition, many species of Quercus would be lumped together according to their geographic and ecological habitat, despite clear distinctions in morphology and, to a large extent, genetic data.
|
|
One common, but sometimes difficult, question is how best to decide which species an organism belongs to, because reproductively isolated groups may not be readily recognizable, and cryptic species may be present. There is a continuum from reproductive isolation with no interbreeding, to panmixis, unlimited interbreeding. Populations can move forward or backwards along this continuum, at any point meeting the criteria for one or another species concept, and failing others. Many of the debates on species touch on philosophical issues, such as nominalism and realism, and on issues of language and cognition.
|
|
Hybrid vigour: Salvia jurisicii x nutans hybrids (top centre, with flowers) are taller than their parents Salvia jurisicii (centre tray) or Salvia nutans (top left). Hybridization between reproductively isolated species often results in hybrid offspring with lower fitness than either parental. However, hybrids are not, as might be expected, always intermediate between their parents (as if there were blending inheritance), but are sometimes stronger or perform better than either parental lineage or variety, a phenomenon called heterosis, hybrid vigour, or heterozygote advantage. This is most common with plant hybrids.
|
|
Harems are a beneficial social structure for the dominant male, as it allows him access to several reproductively available females at a time. Harems provide protection for the females within a particular harem, as dominant males will fiercely ward off potential invaders. This level of protection may also, such in the case of the common pheasant, reduce the energy expended by females on remaining alert to, or fleeing from, invading males. Harems allow bonding and socialization among the female members, which can result in greater control over access to females as determined by the females' preferences.
|
|
Breeding occurs during the winter in populations in the northern and southern parts of the range. In equatorial regions, although only a single breeding season occurs each year for any given population, this may be aligned with either the Northern or Southern Hemisphere winter, so some populations geographically close to one another may, nonetheless, be reproductively isolated. Gestation lasts about three to four months, but in some populations, delayed implantation of the embryo causes birth of the young until five to seven months after mating. The female gives birth to a single young, which is initially blind and partially hairless.
|
|
Breeding stock is a group of animals used for the purpose of planned breeding. When individuals are looking to breed animals, they look for certain valuable traits in purebred animals, or may intend to use some type of crossbreeding to produce a new type of stock with different, and presumably super abilities in a given area of endeavor. For example, when breeding swine for meat, the "breeding stock should be sound, fast growing, muscular, lean, and reproductively efficient." The "subjective selection of breeding stock" in horses has led to many horse breeds with particular performance traits.
|
|
In some seasons, as many as 65% are unable to reach three months of age, possibly due to falls and related injuries, although in some seasons infant mortality is as low as 0%. For those that do survive to adulthood, sexual maturity is attained at 18 to 20 months in females and 32 to 48 months in males. Sexual maturity may take longer to reach in the wild compared to captivity. For females, the inter-birth interval, or time between successive offspring, is typically one year, and in captivity, females can remain reproductively active until the age of 23.
|
|
In > all of these examples the derivative populations grow adjacent to the > parental species, which they resemble closely in morphology, but from which > they are reproductively isolated because of multiple structural differences > in their chromosomes. The spatial relationship of each parental species and > its derivative suggests that differentiation has been recent. The repeated > occurrence of the same pattern of differentiation in Clarkia suggests that a > rapid reorganization of chromosomes has been an important mode of evolution > in the genus. This rapid reorganization of the chromosomes is comparable to > the systemic mutations proposed by Goldschmidt as a mechanism of > macroevolution.
|
|
Not all polyploids are reproductively isolated from their parental plants, and gene flow may still occur for example through triploid hybrid x diploid matings that produce tetraploids, or matings between meiotically unreduced gametes from diploids and gametes from tetraploids. It has been suggested that many of the existing plant and most animal species have undergone an event of polyploidization in their evolutionary history. Reproduction of successful polyploid species is sometimes asexual, by parthenogenesis or apomixis, as for unknown reasons many asexual organisms are polyploid. Rare instances of polyploid mammals are known, but most often result in prenatal death.
|
|
Bees from Bombus and Xylocopa are thought to pollinate these flowers because their adaptive behavior allows them to easily extract pollen that is less available to other insects. Since bees have a source of plentiful pollen that they do not have to compete with other insects for, they are more likely to visit these flowers. This then allows the flowers to be more successful reproductively because the plants maximize their pollen dispersal with each bee visit, and less pollen is lost. The relationship between buzz pollinated plants and bees benefits both groups and could be why poricidal anthers have been successful evolutionarily.
|
|
People infected with these species have a tapeworm infection. In contrast, the four species that cause human coenurosis can only grow into mature, reproductively capable worms inside their definitive hosts, canids such as dogs, wolves, foxes and coyotes. Humans who ingest eggs from any of these four species of Taenia become intermediate hosts, or places where the eggs can mature into larvae but not into adult worms. When humans ingest these eggs, the eggs develop into tapeworm larvae that group within cysts known as coenuri, which can be seen in the central nervous system, muscles, and subcutaneous tissues of infected humans.
|
|
Puberty is the transitory stage in human development in which a person goes from a child into a reproductively mature adult, in other words, puberty is the process of sexual maturation in humans. The onset of puberty varies between boys and girls, with boys usually starting around 11–12 years of age and ending by 16-17,Marshall (1986), pp. 176–177 and girls starting around 10-11 and ending at 15-17. Activity in the hypothalamic–pituitary–gonadal axis (HPG axis) initiates puberty by secreting gonadotropin-releasing hormone (GnRH) from the hypothalamus into the anterior pituitary.
|
|
Epinephelus albomarginatus is classified as Vulnerable by the IUCN because it has a small area of distribution and has been overfished, causing a substantial reduction in the population of reproductively active individuals. It does occur in some protected areas in both South Africa and Mozambique. In South Africa this species is subject to management by a total allowable effort limitation on commercial fisheries as well as by additional restrictions which are designed to protect overfished species. These include a bag limit of 5 fish per person per day and minimum allowable size of 40 cm for landing for recreational fishers.
|
|
Experiments have shown the importance of temperature, but the trigger event, especially in arid regions, is often a storm. In anurans, males usually arrive at the breeding sites before females and the vocal chorus they produce may stimulate ovulation in females and the endocrine activity of males that are not yet reproductively active. In caecilians, fertilisation is internal, the male extruding an intromittent organ, the , and inserting it into the female cloaca. The paired Müllerian glands inside the male cloaca secrete a fluid which resembles that produced by mammalian prostate glands and which may transport and nourish the sperm.
|
|
In the first 24 hours after invasion, host workers undergo a significant change in their chemical bouquets, finishing with a qualitatively similar chemical mix to the invasive queen. Two hypotheses exist for this outcome. The first is that the workers begin to produce their own chemicals in an arms-race pattern to assume reproductive roles in response to the death of their native queen, which happens under normal conditions if a queen dies. The second hypothesis is that these chemicals are in fact applied to workers’ bodies by the invasive queen as she takes over to establish herself as the reproductively dominant individual.
|
|
In some species of anglerfish, when a male finds a female, he bites into her skin, and releases an enzyme that digests the skin of his mouth and her body, fusing the pair down to the blood-vessel level. The male becomes dependent on the female host for survival by receiving nutrients via their shared circulatory system, and provides sperm to the female in return. After fusing, males increase in volume and become much larger relative to free-living males of the species. They live and remain reproductively functional as long as the female lives, and can take part in multiple spawnings.
|
|
In the Sierra de Perijá, Hyalinobatrachium pallidum was abundant and reproductively active at two localities with small fast-flowing creeks surrounded by primary cloud forest and abundant stream-side vegetation. It was scarce at a third locality, a small creek in secondary forest with shaded coffee plantations. The Guacharaquita population was considered almost extirpated by habitat loss in the assessment by the International Union for Conservation of Nature (IUCN) in 2004. However, Rojas-Runjaic and colleagues suggest that the conservation status of this species should be reassessed in light of broader distribution than was known at the time of the assessment.
|
|
The British Ornithologists Union first classed the Scottish crossbill as a separate and distinct species in 1980, but some ornithologists believed there was insufficient scientific research for its status. It was considered to be possibly a race of either the red crossbill or the parrot crossbill, both of which also occur in the Caledonian Forest. RSPB research showed that Scottish crossbills have quite distinct flight and excitement calls from other crossbills - some even stated they have "Scottish accents". Research in Scotland has shown that red, parrot and Scottish crossbills are reproductively isolated, and the diagnostic calls and bill dimensions have not been lost.
|
|
As they grow, they continually moult, adding further segments and legs as they do so. Some species moult within specially prepared chambers of soil or silk, and may also shelter in these during wet weather, and most species eat the discarded exoskeleton after moulting. The adult stage, when individuals become reproductively mature, is generally reached in the final moult stage, which varies between species and orders, although some species continue to moult after adulthood. Furthermore, some species alternate between reproductive and non-reproductive stages after maturity, a phenomenon known as periodomorphosis, in which the reproductive structures regress during non-reproductive stages.
|
|
The original mutations in the flamenco locus inhibited the transcription of the master transcript, thereby deactivating this defense system. A historical example of invasion and Piwi response is known: the P-element transposon invaded a Drosophila melanogaster genome in the mid-20th century, and, through interbreeding, within decades all wild fruit flies worldwide (though not the reproductively isolated lab strains) contained the same P-element. Repression of further P-element activity, spreading near- simultaneously, appears to have occurred by the Piwi-interacting RNA pathway. piRNA clusters in genomes can now readily be detected via bioinformatics methods.
|
|
Collared pikas generally mate with their nearest neighbors and are believed to be facultatively monogamous, but they have also been predicted to participate in polygynandry and reproduce with multiple partners, because males often travel to territories of several females during the spring before mating season begins. The males receive the females around the end of spring. However, the pinnacle of the mating season arises in May and early June. Collared pikas, both male and female, are reproductively developed at one year of age and give birth to two or three young each year in their nests within the talus.
|
|
These bonds motivate males to defend their offspring against infanticide from unrelated individuals and to never commit infanticide against their own offspring. This form of social monogamy has been observed in gibbons, siamangs, baboons, and macaques. One study demonstrated that for gorillas, living in harem-style groups reduces a female's risk of infanticide more than if she mated with multiple males. A female gorilla benefits more from protection by the silverback male, despite the fact that mating with only one male increased paternity certainty and thus increases the number of males in the population that would benefit reproductively from infanticide.
|
|
The "rock-paper- scissors" mating strategy is a genetically-based male polymorphism that has been maintained over millions of years throughout many populations of side- blotched lizard in the United States and Mexico. However, speciation has resulted from the formation of reproductive isolation between populations when a population loses of one or more of the male morphologies. However, speciation due to the loss of a male morph has occurred when populations lose one or more male morphs and become reproductively isolated from populations with the ancestral polymorphism. For side-blotched lizards, the morph lost most commonly is the sneaker male.
|
|
As Banksia species are intolerant of calcareous soils, and are not adapted to long range seed dispersal, the two populations of B. epica appear to be reproductively isolated. Nelson has suggested that there was once a continuous strip of siliceous sand along the coast, providing an extensive and unfragmented habitat for B. epica; rises in the sea level had submerged this strip, leaving only the cliff-top dunes as suitable habitat. The fact that the resultant isolated populations have not perceptibly speciated since then suggests that the species has been fragmented for only a short time, perhaps only since the Last Glacial Maximum.
|
|
When a male finds a female, he bites into her skin, and releases an enzyme that digests the skin of his mouth and her body, fusing the pair down to the blood-vessel level. The male becomes dependent on the female host for survival by receiving nutrients via their shared circulatory system, and provides sperm to the female in return. After fusing, males increase in volume and become much larger relative to free-living males of the species. They live and remain reproductively functional as long as the female lives, and can take part in multiple spawnings.
|
|
Ernst Mayr's 1942 book was a turning point for the species problem. In it, he wrote about how different investigators approach species identification, and he characterized their approaches as species concepts. He argued for what came to be called the Biological Species Concept (BSC), that a species consists of populations of organisms that can reproduce with one another and that are reproductively isolated from other populations, though he was not the first to define "species" on the basis of reproductive compatibility. For example, Mayr discusses how Buffon proposed this kind of definition of "species" in 1753.
|
|
Geobiology, 3: 13-31.. The increase in abundance of the callistophytes coincided with a decline in abundance and diversity of the Lyginopteridales, which occupied very similar ecological niches and were very similar in general habit. It seems possible, therefore, that the reproductively more sophisticated callistophytes were able to out-compete and replace the Lyginopteridales. The Callistophytaceae flourished in Euramerica through Late Pennsylvanian times, eventually becoming extinct as this part of Pangaea became arid at the start of Permian times. They extend through the Permian of China and include anatomically preserved ovules of Callospermarion,Hilton, J., Wang S. J., Zhu W. Q., Tian B., Galtier, J. and Wei A. H. (2002).
|
|
The highest known frequency of reproductively successful extra-pair copulations are found among fairywrens Malurus splendens and Malurus cyaneus where more than 65 percent of chicks are fathered by males outside the supposed breeding pair. This discordantly low level of genetic monogamy has been a surprise to biologists and zoologists, as social monogamy can no longer be assumed to determine how genes are distributed in a species. Elacatinus, also widely known as neon gobies, also exhibit social monogamy. Hetereosexual pairs of fish belonging to the genus Elacatinus remain closely associated during both reproductive and non- reproductive periods, and often reside in same cleaning station to serve client fish.
|
|
The presence of Bougainville as a 'black spot' in an island > world of brownskins (later called redskins) raises a question that cannot > now be answered. Were the genes producing that darker pigmentation carried > by the first Bougainvilleans when they arrived? Or did they evolve by > natural or 'social' selection, during the millennia in which the descendants > of those pioneers remained isolated, reproductively, from neighbouring > islanders? Nothing now known about Bougainville’s physical environment can > support an argument for the natural selection of its peoples' distinctively > black pigmentation; therefore a case might be made for social selection, > namely an aesthetic (and hence reproductive) preference for black > skin.
|
|
The genetic diversity among the Denisovans from Denisova Cave is on the lower range of what is seen in modern humans, and is comparable to that of Neanderthals. However, it is possible that the inhabitants of Denisova Cave were more or less reproductively isolated from other Denisovans, and that, across their entire range, Denisovan genetic diversity may have been much higher. Denisova Cave, over time of inhabitance, continually swung from a fairly warm and moderately humid pine and birch forest to a tundra or forest–tundra landscape. Conversely, Baishiya Karst Cave is situated at a high elevation, an area characterized by low temperature, low oxygen, and poor resource availability.
|
|
M. mexicanus like many ant, wasps and bees, is a eusocial insect species. Eusocial insects are characterized by distinct caste systems, where some individuals breed and most individuals are sterile helpers, and overlapping generations so mother, adult offspring and immature offspring are all living at the same time. In a eusocial colony, an individual is assigned a specialized caste before they become reproductively mature, which makes them behaviorally (and sometimes physiologically) distinct from other castes. The honey pot ants exhibit all of these characteristics within a colony: a queen and males make up the reproductive caste, and the rest of the individuals are sterile female workers.
|
|
In 2012, a transgenic sheep named "Peng Peng" was cloned by Chinese scientists, who spliced his genes with that of a roundworm (C. elegans) in order to increase production of fats healthier for human consumption. In the study of natural selection, the population of Soay sheep that remain on the island of Hirta have been used to explore the relation of body size and coloration to reproductive success. Soay sheep come in several colors, and researchers investigated why the larger, darker sheep were in decline; this occurrence contradicted the rule of thumb that larger members of a population tend to be more successful reproductively.
|
|
Incorporating the concept of genetic relatedness (through IF) is essential because many mutualisms involve the eusocial insects, where the majority of individuals are not reproductively active. The short-term component is chosen because it is operationally useful, even though the role of long-term adaptation is not considered (de Mazancourt et al. 2005). This definition of mutualism should be suffice for this article, although it neglects discussion of the many subtitles of IF theory applied to mutualisms, and the difficulties of examining short-term compared to long-term benefits, which are discussed in Foster and Wenselneers (2006) and de Mazancourt et al. (2005) respectively.
|
|
This species displays subtle variation in morphometric and most sculptural characters across its range except for the sculpture of the base of abdominal tergum IV. This character varies from extremely smooth and shining in the southwest to strongly, dense-punctate and costate along the western edge of the High Plateau. Intergrades are common, however, occurring all along the western coast and into the High Plateau. Both smooth and punctate specimens may be found at the same locales, including Ampotoampoto, Ejada, Tsihombe and Ambinanitelo. The variation of this character indicates that although the two extremes are reproductively isolated by distance and geography, but are otherwise linked across their range by intermediate populations.
|
|
On Guam, the Mariana crow's decline is primarily due to predation by the introduced brown tree snake (Boiga irregularis). In spite of protection of nesting-sites by electrical tree barriers, the remaining birds are considered to be reproductively senescent. On Rota, many other threats endanger the crow, including homestead development, resort and golf-course construction, agricultural settlement, nest-predation from introduced rats, the mangrove monitor lizard (Varanus indicus), typhoons, predation from feral cats, disease, and competition with the black drongo (Dicrurus macrocercus). More recently, the brown tree snake has also been detected on Rota, likely leading to serious declines in the Mariana crow population there if the snake population establishes itself.
|
|
The subpopulations display seasonal fidelity to particular areas, but DNA studies show that they are not reproductively isolated. The 13 North American subpopulations range from the Beaufort Sea south to Hudson Bay and east to Baffin Bay in western Greenland and account for about 54% of the global population.Supplementary material for Ursus maritimus Red List assessment Bears play-fighting The range includes the territory of five nations: Denmark (Greenland), Norway (Svalbard), Russia, the United States (Alaska) and Canada. These five nations are the signatories of the International Agreement on the Conservation of Polar Bears, which mandates cooperation on research and conservation efforts throughout the polar bear's range.
|
|
The condition could also be caused by mycotoxins that can develop when animal feed is stored, and these have the same effect as synthetic hormones. In about 10 percent of cases, if eggs fertilized with male chromosomes are cooled by a few degrees for three days after laying, the relative activity of the sex hormones will favour development of female characteristics. The sex chromosomes work by coding for enzymes that affect the bird's development in the egg and during its life. This cooling will produce a chicken with a fully functioning and reproductively fertile female body-type; even though the chicken is genetically male.
|
|
The introduced Chilean populations of California poppy appear to be larger and more fecund in their introduced range than in their native range (Leger and Rice, 2003). Introduced populations have been noted to be larger and more reproductively successful than native ones (Elton, 1958), and there has been much speculation as to why. An increase in resource availability, decreased competition, and release from enemy pressure have all been proposed as explanations. One hypothesis is that the plant's resources devoted in the native range to a defense strategy can, in the absence of enemies, be devoted to increased growth and reproduction (the EICA Hypothesis, Blossey & Nötzold, 1995).
|
|
Reproductive hierarchies do not occur in newly founded nests, whereas a social dominance structure is developed in reused nests. In newly founded nests, a quasisocial organization is found in which all founding members are reproductive and a social hierarchy does not exist. Once a nest enters its second or later year of use, the first female to eclose takes on a reproductively dominant status resulting in a semisocial organization. This difference in eclosion rate can be as close as a few days; a female emerging from her pupa only a day before the other offspring in the nest is sufficient to establish the reproductive hierarchy.
|
|
Human males live largely in monogamous societies like gorillas, and therefore testis size is smaller in comparison to primates in multi-male breeding systems, such as chimpanzees. The reason for the differentiation in testis size is that in order to succeed reproductively in a multi-male breeding system, males must possess the ability to produce several fully fertilising ejaculations one after another. This, however, is not the case in monogamous societies, where a reduction in fertilising ejaculations has no effect on reproductive success. This is reflected in humans, as the sperm count in ejaculations is decreased if copulation occurs more than three to five times in a week.
|
|
Trees that support smaller numbers of Indiana bats from the same maternity colony are designated as alternate roosts. In cases where smaller maternity colonies are present in an area, primary roosts may be defined as those used for more than 2 days at a time by each bat, while alternate roosts are generally used 1 day. Maternity colonies may use up to three primary roosts and up to 33 alternate roosts in a single season. Reproductively active females frequently switch roosts to find optimal roosting conditions. When switching between day roosts, Indiana bats may travel as little as 23 feet (7 m) or as far as 3.6 miles (5.8 km).
|
|
The impact of escapees from aquaculture operations depends on whether or not there are wild conspecifics or close relatives in the receiving environment, and whether or not the escapee is reproductively capable. Several different mitigation/prevention strategies are currently employed, from the development of infertile triploids to land-based farms which are completely isolated from any marine environment. Escapees can adversely impact local ecosystems through hybridization and loss of genetic diversity in native stocks, increase negative interactions within an ecosystem (such as predation and competition), disease transmission and habitat changes (from trophic cascades and ecosystem shifts to varying sediment regimes and thus turbidity). The accidental introduction of invasive species is also of concern.
|
|
California sheephead can transition from a reproductively functional female to a functional male during the course of a lifespan in response to social factors. Protogynous sex change typically follows the size-advantage model, where gonadal transformation occurs once the reproductive potential of an individual would be greater as a male than as a female. The transitional phase takes between two weeks and several months, and steroid hormone concentrations are thought to be related to sex change due to the total degradation of the ovaries and the appearance of testes. The exact timing of the sexual morphogenesis is suppressed by aggressive interactions with dominant males and triggered by the removal of alpha males.
|
|
In order to address some of these concerns some GMOs have been developed with traits to help control their spread. To prevent the genetically modified salmon inadvertently breeding with wild salmon, all the fish raised for food are females, triploid, 99% are reproductively sterile, and raised in areas where escaped salmon could not survive. Bacteria have also been modified to depend on nutrients that cannot be found in nature, and genetic use restriction technology has been developed, though not yet marketed, that causes the second generation of GM plants to be sterile. Other environmental and agronomic concerns include a decrease in biodiversity, an increase in secondary pests (non-targeted pests) and evolution of resistant insect pests.
|
|
Other ethical considerations arise with the application of ART to women of advanced maternal age, who have higher changes of medical complications (including pre-eclampsia), and possibly in the future its application to post-menopausal women. Also, ethical issues of human enhancement arise when reproductive technology has evolved to be a potential technology for not only reproductively inhibited people but even for otherwise re-productively healthy people. On the negative aspect of, if this matter is shipped all over the country between dissimilar sperm banks how can we keep up who is from what genetic descent? Where this may quite possibly lead to inner familial (in the genetic sense) marriages, causing numerous genetic flaws in future generations.
|
|
During his career over 40 years he collected more than 4000 isolates of these species in Scandinavia, Germany, Italy, Greece, USA, Canada, Estonia, Belarus, Siberia and China. Initially, following Veikko Hintikka's discovery of a technique to distinguish between Armillaria species by growing them together as single spore isolates on petri dishes and observing changes in the morphology of the cultures, Korhonen showed in 1978 that the European Armillaria mellea species complex could be separated into five reproductively isolated species. Similarly he studied the sexual incompatibility of bipolar systems also in Heterobasidion. As result of these studies the genus Heterobasidion was divided into three species while Armillaria has by now been divided into more than 40 species.
|
|
Male Drosophila pseudoobscura The best-documented creations of new species in the laboratory were performed in the late 1980s. William Rice and G.W. Salt bred fruit flies, Drosophila melanogaster, using a maze with three different choices of habitat, such as light/dark and wet/dry. Each generation was placed into the maze, and the groups of flies that came out of two of the eight exits were set apart to breed with each other in their respective groups. After thirty-five generations, the two groups and their offspring were isolated reproductively because of their strong habitat preferences: they mated only within the areas they preferred, and so did not mate with flies that preferred the other areas.
|
|
In consideration of Pacific salmon for listing under the Act, NMFS has relied on the evolutionarily significant unit (ESU) concept and previous developed a policy on the definition of species under the Act (56 FR 58612– 58618; November 20, 1991). The policy applies only to species of salmonids native to the Pacific. Under this policy, a stock of Pacific salmon is considered a DPS if it represents an evolutionarily significant unit (ESU) of a biological species. A stock must satisfy two criteria to be considered an ESU: (1) It must be substantially reproductively isolated from other conspecific population units; and (2) It must represent an important component in the evolutionary legacy of the species.
|
|
Enantiomers of chiral compounds have similar chemical and physical properties, but can be metabolized by the body differently. This was looked at in bowhead whales (Balaena mysticetus) for two main reasons: they are large animals with slow metabolisms (meaning PCBs will accumulate in fatty tissue) and few studies have measured chiral PCBs in cetaceans. They found that the average PCB concentrations in the blubber were approximately four times higher than the liver; however, this result is most likely age- and sex-dependent. As reproductively active females transferred PCBs and other poisonous substances to the fetus, the PCB concentrations in the blubber were significantly lower than males of the same body length (less than 13 meters).
|
|
Parsimony is part of a class of character-based tree estimation methods which use a matrix of discrete phylogenetic characters to infer one or more optimal phylogenetic trees for a set of taxa, commonly a set of species or reproductively isolated populations of a single species. These methods operate by evaluating candidate phylogenetic trees according to an explicit optimality criterion; the tree with the most favorable score is taken as the best estimate of the phylogenetic relationships of the included taxa. Maximum parsimony is used with most kinds of phylogenetic data; until recently, it was the only widely used character-based tree estimation method used for morphological data. Estimating phylogenies is not a trivial problem.
|
|
Horizontal transfer of parthenogenesis- inducing Wolbachia, which has been observed in Trichogramma wasps, causes infected females to asexually produce fertile females and nonfunctional males. The effects of this include potential speciation of Trichogramma, if Wolbachia is maintained long enough for genetic divergence to occur and for a new species of asexual wasps to become reproductively isolated. Transmission of the bacterium through horizontal transfer has been observed within the same species and among different species of Trichogramma, including T. kaykai, T. deion, T. pretiosum, and T. atopovirilia; however, limitations to transmission exist. In vitro successful horizontal transfer is uncommon within Trichogramma, which suggests that the density of Wolbachia must be relatively high inside of the hosts' ovaries.
|
|
Most genetics- based measures of diversity have been estimated from the analysis of one genetic marker (e.g. LSU, ITS2, or cp23S), yet in recent studies these and other markers were analyzed in combination. The high concordance found among nuclear, mitochondrial and chloroplast DNA argues that a hierarchical phylogenetic scheme, combined with ecological and population genetic data, can unambiguously recognize and assign nomenclature to reproductively isolated lineages, i.e. species. The analysis of additional phylogenetic markers show that some Symbiodinium that were initially identified by slight differences in ITS sequences may comprise members of the same species whereas, in other cases, two or more genetically divergent lineages can possess the same ancestral ITS sequence.
|
|
This stricter definition includes polyploid hybrid taxa but only encompasses a handful of well studied cases of homoploid hybrid speciation, e.g. Heliconius heurippa, Passer italiae, and three Helianthus sunflower species because for most suggested examples of homoploid hybrid speciation, the genetic basis of reproductive isolation is still unknown. Hybrid species can occupy an ecological niche different to those of the parents and may be isolated from the parent species primarily through pre- mating barriers (hybrid speciation with external barriers). Hybrid species may also be reproductively isolated from the parent species through sorting of incompatibilities leading to new combinations of parental alleles that are incompatible with both parent species but compatible within the hybrid taxon (recombinational hybrid speciation).
|
|
This theory is directly relevant and compatible with those two already mentioned, Life History and Parental Investment. Males tend to appear oriented towards short-term mating (greater desire for short-term mates than women, prefer larger number of sexual partners, and take less time to consent to sexual intercourse) and this appears to solve a number of adaptive problems including using fewer resources to access a mate. Although there are a number of reproductive advantages to short-term mating, males still pursue long-term mates, and this is due to the possibility of monopolizing a female's lifetime reproductive resources. Consistent with findings, for both short-term and long-term mates, males prefer younger females (reproductively valuable).
|
|
An additional factor contributing to the status of the Devils River minnow is the introduction of foreign species. Some introduced tropical and game species now compete with the Devils River minnow for food and spatial resources. Several nonnative species of catfish, cichlids, and bass have begun to reduce the minnow species’ numbers by feeding on both the minnows themselves and their main diet of algae and microorganisms. Loricariid catfish in particular have established large populations in the Texan habitats of the Devils River Minnow and are steadily consuming most of the available food. Largemouth bass also prey on the species’ juveniles during winter months, therefore reducing the amount of reproductively mature individuals.
|
|
Genetic divergence is the process in which two or more populations of an ancestral species accumulate independent genetic changes (mutations) through time, often after the populations have become reproductively isolated for some period of time. In some cases, subpopulations living in ecologically distinct peripheral environments can exhibit genetic divergence from the remainder of a population, especially where the range of a population is very large (see parapatric speciation). The genetic differences among divergent populations can involve silent mutations (that have no effect on the phenotype) or give rise to significant morphological and/or physiological changes. Genetic divergence will always accompany reproductive isolation, either due to novel adaptations via selection and/or due to genetic drift, and is the principal mechanism underlying speciation.
|
|
Furthermore, because humans are rarely in direct contact with wild animals and introduce pathogens through "soft contact", the term "sapronotic agents" must be introduced. Sapronoses (Greek sapros "decaying") refers to human diseases that harbor the capacity to grow and replicate (not just survive or contaminate) in abiotic environments such as soil, water, decaying plants, animal corpses, excreta, and other substrata. Additionally, sapro-zoonoses can be characterized as having both a live host and a non-animal developmental site of organic matter, soil, or plants. It must be noted that obligate intracellular parasites that cannot replicate outside of cells and are entirely reproductively reliant on entering the cell to use intracellular resources such as viruses, rickettsiae, chlamydiae, and Cryptosporidium parvum cannot be sapronotic agents.
|
|
It belongs to the subfamily Symmocinae, which is sometimes included in the case-bearers (Coleophoridae) or united with the concealer moth subfamily Autostichinae. Originally described as Recurvaria quadripuncta by A.H. Haworth in 1828, the four-spotted yellowneck is the type species of the genus Oegoconia, which in turn is the type genus of the symmocid subfamily Oegoconiinae (or tribe Oegoconiini, if the symmocids are merged into another family).Pitkin & Jenkins (2004), ABRS (2008), ToL (2008), FE (2009) This species has been confused with its extremely similar but reproductively isolated congener O. deauratella. This is because O. quadripuncta has a junior synonym Oecophora deauratella (established by H.T. Stainton in 1849), while the actual O. deauratella was described (as Lampros deauratella) by G.A.W. Herrich-Schäffer only in 1854.
|
|
This can lead to a decreasing population, especially in species that do not breed often under normal circumstances or become reproductively mature late in life. Another problem is that the decrease in the population of a species due to fisheries can lead to a decrease in genetic diversity, resulting in a decrease in bio-diversity of a species. If the species diversity is decreased significantly, this could cause problems for the species in an environment that is so variable and quick- changing; they may not be able to adapt, which could result in a collapse of the population or ecosystem. Another threat to the productivity and ecosystems of upwelling regions is El Niño-Southern Oscillation (ENSO) system, or more specifically El Niño events.
|
|
In 2008, Blanchard was the lead author of an influential paper proposing the introduction of hebephilia in the DSM-5. The paper, coauthored mostly with colleagues from CAMH and the University of Toronto, triggered a number of reactions, many of them critical on the basis that it pathologizes reproductively valid behavior in order to uphold current social and legal standards. Critics include Richard Green, DSM-IV editor Michael First, forensic psychologist Karen Franklin, and Charles Allen Moser, while others including William O'Donohue argued that the proposal did not go far enough. Blanchard also wrote the literature review paper for the DSM-5 committee regarding pedophilia, in which he summarized and attempted to address the criticism over the DSM-IV-TR definition of pedophilia.
|
|
Evolution 55 (7): 1452–1463 The Andersson experiment demonstrated that female long-tailed widowbirds prefer supernormal tails, as males with elongated tails were found to be the most reproductively successful. The tail females found most attractive were longer than those that occur in the natural setting. This outcome was shown to be the result of female choice rather than differences in male behavior resulting from shortened tails: males with shortened tails neither became less active in courtship display, nor did they give up their breeding territories. Thus, the tail is used to attract females rather than in direct contests among males, which is further supported by the fact that males do not expand their tails during flight displays during territorial contests.
|
|
Mayr emphasized the importance of allopatric speciation, where geographically isolated sub-populations diverge so far that reproductive isolation occurs. He was skeptical of the reality of sympatric speciation believing that geographical isolation was a prerequisite for building up intrinsic (reproductive) isolating mechanisms. Mayr also introduced the biological species concept that defined a species as a group of interbreeding or potentially interbreeding populations that were reproductively isolated from all other populations. Before he left Germany for the United States in 1930, Mayr had been influenced by the work of the German biologist Bernhard Rensch, who in the 1920s had analyzed the geographic distribution of polytypic species, paying particular attention to how variations between populations correlated with factors such as differences in climate.
|
|
In the 8th and final novel of the series, Cross of Blood, it was confirmed that Humans and Newcomers are (potentially) reproductively compatible, when Cathy Frankel (a Tenctonese female) became pregnant with Matthew Sikes' (a human male) child without the aid of a binnaum. In this case, unlike the normal Tenctonese gestation cycle, the Newcomer female carried the child for the full term of the pregnancy. However, the resulting offspring did not survive beyond the first few weeks of his birth, due to physiological incompatibilities resulting from his Tenctonese biology trying to overtake/override his human biology. This may have been a natural result of the pairing, or the result of tampering as the child had been kidnapped at birth and held by a Purist cell.
|
|
To live on a diet of cephalopods, smaller sharks, and bony fish, the frilled shark practices diel vertical migration to feed at night at the surface of the ocean. When hunting food, the frilled shark moves like an eel, bending and lunging to capture and swallow whole prey with its long and flexible jaws, which are equipped with 300 recurved, needle-like teeth. Reproductively, the two species of frilled shark, C. anguineus and C. africana, are aplacental viviparous animals, born of an egg, without a placenta to the mother shark. Contained within chondrichthyes (egg capsules) the shark embryos develop in the mother's body; at birth, the infant sharks emerge from their egg capsules in the uterus, where they feed on yolk.
|
|
The extant species of frilled shark, C. anguineus and C. africana, do not have a defined breeding season, because their oceanic habitats register no seasonal influence from the ocean's surface; the male shark reaches sexual maturity when he is long, and the female shark reaches sexual maturity when she is long. The mature female shark has two ovaries and a uterus, which is in the right side of her body; ovulation occurs fortnightly; and pregnancy ceases vitellogenesis (yolk formation) and the production of new ova. Both ovulated eggs and early-stage shark embryos are enclosed in chondrichthyes, ellipsoid egg-cases made of a thin, golden-brown membrane. Reproductively, the frilled shark is an aplacental viviparous animal born from an egg, without a placenta to the mother shark.
|
|
None was large enough to have been reproductively mature (see below) and would have needed to survive in any new habitat for several months before reproducing. Passive dispersal may also occur via weed on boats and boat trailers and via water pumped from one waterbody to another for industrial and irrigation purposes. In the Nseleni River juvenile Tarebia granifera were commonly found with another invasive snail, Pseudosuccinea columella, on floating clumps of water hyacinth Eichhornia crassipes which provide a vehicle for rapid downstream dispersal. Once established in a particular waterbody Tarebia granifera is likely to disperse actively, both up and downstream in the case of flowing systems, as far as environmental factors like current speed and food availability will allow.
|
|
This form of speciation occurs when the geographical isolation of a sub-population is followed by the development of mechanisms for reproductive isolation. Mayr also formulated the biological species concept that defined a species as a group of interbreeding or potentially interbreeding populations that were reproductively isolated from all other populations. In the 1944 book Tempo and Mode in Evolution, George Gaylord Simpson showed that the fossil record was consistent with the irregular non-directional pattern predicted by the developing evolutionary synthesis, and that the linear trends that earlier paleontologists had claimed supported orthogenesis and neo-Lamarckism did not hold up to closer examination. In 1950, G. Ledyard Stebbins published Variation and Evolution in Plants, which helped to integrate botany into the synthesis.
|
|
Annual spawning occurs in specific locations on the outer reef shelf during the days around the full moon of December and January. Aggregations can range anywhere from a dozen to up to several thousand adult individuals and are usually in the same site each year, making an easy target for fishermen. This intensive harvesting of reproductively active individuals, often before they have had the chance to spawn, has resulted in a marked decline in both abundance and size. One site for example, Caye Glory, historically provided a catch of up to 1,200–1,800 Nassau groupers per boat per spawning season during the 1960s. In 2001, at the same site, fishers caught just 9 individuals out of an aggregation of 21 groupers.
|
|
The Newfoundland pine marten (Martes americana atrata) is a genetically distinct subspecies of the American marten (Martes americana) found only on the island of Newfoundland in the province of Newfoundland and Labrador, Canada; it is sometimes referred to as the American marten (Newfoundland population) and is one of only 14 species of land mammals native to the island. The marten was listed as endangered by the COSEWIC in 2001 and has been protected since 1934, however the population still declines. The Newfoundland marten has been geographically and reproductively isolated from the mainland marten population for 7000 years. The Newfoundland pine marten is similar in appearance to its continental cousin, but is slightly larger, with dark brown fur with an orange/yellow patch on the throat.
|
|
Guafo Island is characterized by a high biodiversity that includes the largest breeding colony of South American fur seals (Arctocephalus australis) on Chilean coasts, a large population of South American sea lions (Otaria byronia), and a reproductively active population of marine otters (Lontra felina), a critically endangered species. Recently the coasts of the island have been indicated as an important feeding area of blue whales (Balaenopteramusculus), Southern right whale (Eubalaena australis), humpback whales (Megaptera novaeangliae) and transient killer whales (Orcinus orca). Among seabird highlights is the largest breeding colony of sooty shearwater (Puffinusgriseus) in the world (Reyes-Arriagada et al. 2007) as well as important nesting sites of Magellanic penguins (Spheniscus magellanicus) and occasional sightings of Humboldt penguins (Spheniscus humboldti).
|
|
Senecio eboracensis is a hybrid species whose parents are the self-incompatible and promiscuous Sicilian Senecio squalidus (also known as Oxford ragwort) and the self- compatible and tenacious Senecio vulgaris (also known as Common groundsel). Like S. vulgaris, S. eboracensis is self-compatible but shows little or no natural crossing with its parent species and is therefore reproductively isolated, indicating that strong breeding barriers exist between this new hybrid and its parents. It is thought to have resulted from backcrossing of the F1 hybrid of its parents to S. vulgaris. S. vulgaris is native to Britain, while S. squalidus was introduced from Sicily in the early 18th century; therefore, S. eboracensis has speciated from those two species within the last 300 years.
|
|
866 This last specimen, a male, had its testicles located in the scrotum, and therefore was reproductively mature, even though its skull bones were not completely fused, indicating it was not yet osteologically mature. Before it was collected in 2002, the species was not recorded in earlier biological surveys of Anjozorobe, taking place in 1977–1986 and 1996; whether this is because the animal is difficult to collect, because its abundance varies from year to year, or because its distribution is patchy is unknown. Goodman and colleagues argued on the basis of this example that rapid surveys may not necessarily yield complete inventories of the fauna of an area. Later surveys in 2005 and 2006 did find it at several other sites in the region, at some of which it was abundant.
|
|
According to Williamson, these successful hybridisations would most likely occur in organisms with external fertilisation or male gamete dispersal. He acknowledges in his work Larvae and Evolution to have borrowed the idea of hybridogenesis from the well-known process of interspecific hybridisation that take place in plants. Hybrid plants generated from phylogenetically distant species can often give rise to new species if the hybrids become reproductively isolated from the progenitor populations. In one of his articles Williamson contends that # there were no true larvae until after the establishment of classes in the respective phyla, # early animals hybridised to produce chimeras of parts of dissimilar species, # the Cambrian explosion resulted from many such hybridisations, # modern animal phyla and classes were produced by such early hybridisations, rather than by the gradual accumulation of specific differences.
|
|
Regarding sexual orientation, he states that true homosexuals are rare; that only 6% of the male population engages in any sort of homosexual behavior in their lifetime, and that 80% of those also have sex with women, so he focuses on bisexuality. "It seems most likely that exclusive homosexuality is a genetic by-product of the reproductively advantageous characteristic of bisexuality. If so, homosexual behaviour joins the ranks of a number of other human characteristics that are advantageous when a person has inherited a few of the relevant genes, but disadvantageous if they have inherited more." Bisexuality in both men and women is explained as an adaptive trait because it provides earlier opportunities to gain sexual experience, and more opportunities to practice skills such as infidelity and interacting with people of different personalities.
|
|
The molecular interpretation of these signals is through the transmission of a complex signal known as florigen, which involves a variety of genes, including Constans, Flowering Locus C and Flowering Locus T. Florigen is produced in the leaves in reproductively favorable conditions and acts in buds and growing tips to induce a number of different physiological and morphological changes. The first step of the transition is the transformation of the vegetative stem primordia into floral primordia. This occurs as biochemical changes take place to change cellular differentiation of leaf, bud and stem tissues into tissue that will grow into the reproductive organs. Growth of the central part of the stem tip stops or flattens out and the sides develop protuberances in a whorled or spiral fashion around the outside of the stem end.
|
|
When speciation is not driven by (or strongly correlated with) divergent natural selection, it can be said to be nonecological, so as to distinguish it from the typical definition of ecological speciation: "It is useful to consider ecological speciation as its own form of species formation because it focuses on an explicit mechanism of speciation: namely divergent natural selection. There are numerous ways other than via divergent natural selection in which populations might become genetically differentiated and reproductively isolated." It is likely that many instances of nonecological speciation are allopatric, especially when the organisms in question are poor dispersers (e.g., land snails, salamanders), however sympatric nonecological speciation may also be possible, especially when accompanied by an "instant" (at least in evolutionary time) loss of reproductive compatibility, as when polyploidization happens.
|
|
In this species, as in related species, the workers may become reproductively capable, and the queen's ability to prevent this depends on the size of the colony and the difference in size between the queen and the workers. Abstract Foraging adults are preyed on by crab spiders and predatory bugs while ants are the main predators of the nests, especially unguarded nests, although they may attack guarded nests by overcoming the guard bee. The main parasites of the adult females are flies of the family Conopidae, while flies of the family Phoridae will lay eggs within the nests, tailgating returning workers to get past the guards. The parasitic beetle Ripiphorus walshi is a larval parasite and its triungulin larvae attach themselves to the adults when they visit flowers and are transported back to the nest.
|
|
Ficus exasperata, fruits Each species of fig is pollinated by one or a few specialised wasp species, and therefore plantings of fig species outside of their native range results in effectively sterile individuals. For example, in Hawaii, some 60 species of figs have been introduced, but only four of the wasps that fertilize them have been introduced, so only four species of figs produce viable seeds there and can become invasive species. This is an example of mutualism, in which each organism (fig plant and fig wasp) benefit each other, in this case reproductively. The intimate association between fig species and their wasp pollinators, along with the high incidence of a one-to- one plant-pollinator ratio have long led scientists to believe that figs and wasps are a clear example of coevolution.
|
|
Other scientists, noting that other primates have not evolved neoteny to the same extent as humans despite fertility being as reproductively significant for them, argue that if human children need more parental investment than nonhuman primate young, that would have selected for a preference for more experienced females more capable of providing parental care. As this would make experience more relevant for effective reproductive success (producing offspring that survive to reproductive age, as opposed to simply the number of births) and therefore more able to compensate for a slight to moderate decrease in biological fertility from recent sexual maturity to late pre-menopausal life, these scientists argue that the sexual selection model of neoteny makes the false prediction that primates that need less parental investment than humans should display more neoteny than humans.
|
|
Linnaea borealis ssp. longiflora in the Mount Baker-Snoqualmie National Forest, Washington, U.S. clonal colonies Linnaea borealis has a circumpolar distribution in moist subarctic, boreal, or cool temperate forests, extending further south at higher elevations in various mountains, in Europe south to the Alps, in Asia south to northern Japan, and in North America south to northern California and to Arizona and New Mexico in the west, and to West Virginia (and formerly Tennessee) in the Appalachian Mountains in the east. Linnaea borealis is self-incompatible, requiring cross-pollination to produce viable seeds; since pollen dispersal is usually not far, individuals and clonal colonies can become reproductively isolated. Regardless of seed production, Linnaea plants in a particular area often spread by stolons to form clonal patches of the same genotype.
|
|
Many fishermen generally release dusky flatead over 70 cm, believing that they are important large breeding females. The hypothesis that dusky flathead over 70 cm are "important large breeding females" is questionable. A study by Pollock (2014) shows that the vast majority of eggs produced by the annual spawning aggregation come from the mid-size females (50 cm–60 cm), but more importantly the large females over 70 cm are often reproductively senescent—that is they have degenerate ovaries in which the eggs are breaking down or have broken down, and are not shed. A study is currently underway in northern New South Wales which is finding at most of the large female flathead (>75 cm) also have degenerate ovaries during the early spawning period (Nov/Dec), whereas the mid-size females have healthy ovaries with developing yolky eggs.
|
|
In 2013, the 4th District Court of Appeal held that a developmentally disabled adult with "mild mental retardation" may be reproductively sterilized if the court determines there is clear and convincing evidence that the procedure is medically necessary for the patient. The court held that Probate Code section 2357 regulated the patients court order for medical treatment because the sterilization was incidental to acquiring medical care and not the purpose of the medical treatment; alternatively, Probate Code section 1950 et seq. applies when the objective is to prevent the patient from bearing children. In 1985, the Supreme Court of California held that a California statute that completely prohibits the sterilization of the developmentally disabled is overbroad and unconstitutional because a mentally incompetent person has a constitutional right to sterilization if a less intrusive method of birth control is not available.
|
|
The males of the Astatotilapia burtoni come in two phenotypes that are reversible. The males can readily switch between being territorial and non-territorial based on the social environment they are in: dominant, territorial males possess bright coloration, aggressive behavior while defending territory, and an active role in sexually reproducing with the females; on the other hand, subordinate and non-territorial males possess coloration similar that of the females, lack initiative to pursue female counterparts, and are reproductively suppressed due to regressed gonads. The transitions between different social roles cause several changes in the brain and reproductive system, such that the social transformation affects them both behaviorally and physically. To expand on reversibility, if a territorial male is placed with an individual that is significantly larger in size, it will then rapidly socially transform into the non-territorial type.
|
|
In Bacillus megaterium and Bacillus subtilis, POR is a C-terminal domain of CYP102, a single-polypeptide self-sufficient soluble P450 system (P450 is an N-terminal domain). The general scheme of electron flow in the POR/P450 system is: The definitive evidence for the requirement of POR in cytochrome-P450-mediated reactions came from the work of Lu, Junk and Coon, who dissected the P450-containing mixed function oxidase system into three constituent components: POR, cytochrome P450, and lipids. Since all microsomal P450 enzymes require POR for catalysis, it is expected that disruption of POR would have devastating consequences. POR knockout mice are embryonic lethal, probably due to lack of electron transport to extrahepatic P450 enzymes since liver-specific knockout of POR yields phenotypically and reproductively normal mice that accumulate hepatic lipids and have remarkably diminished capacity of hepatic drug metabolism.
|
|
Cross-cultural data shows that the reproductive success of women is tied to their youth and physical attractiveness such as the pre- industrial Sami where the most reproductively successful women were 15 years younger than their man. One study covering 37 cultures showed that, on average, a woman was 2.5 years younger than her male partner, with the age difference in Nigeria and Zambia being at the far extreme of 6.5 to 7.5 years. As men age, they tend to seek a mate who is ever younger. 25% of eHarmony's male customers over the age of 50 request to only be matched with women younger than 40. A 2010 OkCupid study, of 200,000 users found that female desirability to its male users peaks at age 21, and falls below the average for all women at 31.
|
|
Biologically females tend to select mates "who are most likely to secure offspring survival and thus increase the likelihood that her genetic contribution will be reproductively viable." Studies have suggested that people might be using odor cues associated with the immune system to select mates. Using a brain-imaging technique, Swedish researchers have shown that gay and straight males' brains respond in different ways to two odors that may be involved in sexual arousal, and that the gay men respond in the same way as straight women, though it could not be determined whether this was cause or effect. The study was expanded to include lesbian women; the results were consistent with previous findings that lesbian women were not as responsive to male-identified odors, while their response to female cues was similar to that of straight males.
|
|
The wild-type salmon takes 24 to 30 months to reach market size (4–6 kg) whereas the GM salmon require 18 months for the GM fish to achieve this.Environmental Assessment for AquAdvantage Salmon AquaBounty argue that their GM salmon can be grown nearer to end- markets with greater efficiency (they require 25% less feed to achieve market weight) than the Atlantic salmon which are currently reared in remote coastal fish farms, thereby making it better for the environment, with recycled waste and lower transport costs. To prevent the genetically modified fish inadvertently breeding with wild salmon, all the fish raised for food are females, triploid, and 99% are reproductively sterile. The fish are raised in a facility in Panama with physical barriers and geographical containment such as river and ocean temperatures too high to support salmon survival to prevent escape.
|
|
Many non-human animals have been shown to be able to distinguish between potential partners, based upon levels of FA. As with humans, lower levels of FA are seen in the most reproductively successful members of species. For instance, FA of male forewing length seem to have an important role in successful mating for many insect species, such as dark-wing damselflies and Japanese scorpionflies. In the dark-winged damselfly (Calopteryx maculate), successfully mating male flies showed significantly lower levels of FA in their forewings than unsuccessful males, while for Japanese scorpionflies, FA levels are a good predictor for the outcome of fights between males in that more symmetrical males won significantly more fights. Other animals also show similar patterns, for example, many species of butterfly, males with lower levels of FA tended to live longer and flew more actively, allowing them to have more reproductive success.
|
|
Pinus johannis is a recently described pinyon pine, discovered by Elbert L. Little in 1968 when comparing pinyons growing in Arizona with those of typical Mexican pinyon (Pinus cembroides) in Mexico; he described it as a variety of Mexican pinyon, Pinus cembroides var. bicolor, noting the very different stomatal placing on the leaves; it also differs in needle number, with 3–4 per fascicle, rather than 2–3; in the cones having thinner scales; and in having a denser, more rounded crown. Further research by the French botanist Marie-Françoise Robert-Passini, the American botanists Dana K. Bailey and Frank G. Hawksworth and others, has shown that it is better treated as a distinct species. Although often occurring together with Mexican pinyon, it is reproductively isolated from that by its pollination being a month to two months later in summer, rather than in spring, thereby preventing hybridisation.
|
|
This is in contrast to cladogenesis—or speciation in a sense—in which a population is split into two or more reproductively isolated groups and these groups accumulate sufficient differences to become distinct species. The punctuated equilibria hypothesis suggests that anagenesis is rare and that the rate of evolution is most rapid immediately after a split which will lead to cladogenesis, but does not completely rule out anagenesis. Distinguishing between anagenesis and cladogenesis is particularly relevant in the fossil record, where limited fossil preservation in time and space makes it difficult to distinguish between anagenesis, cladogenesis where one species replaces the other, or simple geographic immigration/emigration patterns. Recent evolutionary studies are looking at anagenesis and cladogeneis for possible answers in developing the hominin phylogenetic tree to understand morphological diversity and the origins of Australopithecus anamensis, and this case could possibly show anagenesis in the fossil record.
|
|
It was concluded that larger foundresses are more reproductively fit and thus JH, which is responsible for the growth and maturation of the ovaries, be more active within these individuals compared to the smaller, less fertile foundresses though the mechanism of action and/or any synergistic effects between JH and other hormones remains unknown. The effect of relative rank on stress hormone levels in savanna baboons The hormone model of dominance and reproductive capacity has also been demonstrated in the naked mole-rat (Heterocephalus glaber). It has previously been established that the dominance hierarchy within the species is dependent on the highest ranking female (queen) and her ability to suppress critically important reproductive hormones in male and female sub- dominants. In sub-dominant males, appears that lutenizing hormone and testosterone are suppressed while in females it appears that the suppression involves the entire suppression of the ovarian cycle.
|
|
Emery's rule is also applicable to members of other kingdoms such as fungi, red algae, and mistletoe. The significance and general relevance of this pattern are still a matter of some debate, as a great many exceptions exist, though a common explanation for the phenomenon when it occurs is that the parasites may have started as facultative parasites within the host species itself (such forms of intraspecific parasitism are well-known, even in some species of bees), but later became reproductively isolated and split off from the ancestral species, a form of sympatric speciation. When a parasitic species is a sister taxon to its host in a phylogenetic sense, the relationship is considered to be in "strict" adherence to Emery's rule. When the parasite is a close relative of the host but not its sister species, the relationship is in "loose" adherence to the rule.
|
|
Confusion has surrounded the nomenclature and taxonomy of the species now known as Armillaria gallica, paralleling that surrounding the genus Armillaria. The type species, Armillaria mellea, was until the 1970s believed to be a pleiomorphic species with a wide distribution, variable pathogenicity, and one of the broadest host ranges known for the fungi. In 1973, Veikko Hintikka reported a technique to distinguish between Armillaria species by growing them together as single spore isolates on petri dishes and observing changes in the morphology of the cultures. Using a similar technique, Kari Korhonen showed in 1978 that the European Armillaria mellea species complex could be separated into five reproductively isolated species, which he named "European Biological Species" (EBS) A through E. About the same time, the North American A. mellea was shown to be ten different species (North American Biological Species, or NABS I through X); NABS VII was demonstrated shortly after to be the same species as EBS E. Because several research groups had worked with this widely distributed species, it was assigned several different names.
|
|
Published research attempts to identify the issues that matter most as couples decide between IVF-ICSI and vasectomy reversal, two very different approaches to family building. This research has generally taken the form of cost-effectiveness or cost-benefit analyses and decision analyses and Markov modeling. Since it is difficult to perform randomized, blinded prospective trials on couples in this situation, analytic modeling can help uncover what variables affect outcomes the most. From this body of work, it has been observed that vasectomy reversal can be the most cost-effective way to build a family if: (a) the female partner is reproductively healthy, and (b) the surgeon can achieve good vasectomy reversal outcomes. If the surgeon can achieve high “patency” rates (moving sperm in the ejaculate) after vasectomy reversal, then vasectomy reversal is competitive with IVF-ICSI. In the special instance of couples with advanced maternal age (defined as a female partner > 38 years old), case series’ have reported that pregnancy rates with vasectomy reversal are competitive with IVF-ICSI.
|
|