They suggest that monogamy would have therefore given males an advantage when producing offspring.
|
|
Not marrying and producing offspring is considered unfilial and Chinese society traditionally views the unmarried as less than full adults.
|
|
I was like, 'OK, so now I'm 25 I can somehow afford £28 [$36] for the privilege of not producing offspring?
|
|
It's believed that if there are enough sterile males mating with females, the chances of producing offspring are reduced, and the population crashes.
|
|
He has been collecting exes and producing offspring, growing gray and shaggy and looking after his son Jackson (Azhy Robertson) while living in Jackson's mother's garage.
|
|
A team of researchers in Brazil made this realization with several lines of evidence, noting that this frog's sex chromosomes require a whole different way of producing offspring.
|
|
"If humans ever start to live permanently in space, assisted reproductive technology using preserved spermatozoa will be important for producing offspring," the researchers write in their paper published today in Proceedings of the National Academy of Sciences.
|
|
In China, where producing offspring is seen as an important filial obligation, pressure to get married and give birth can be overwhelming, so much so that people seek this temporary – and pricey – solution to appeasing their parents and other relatives.
|
|
In addition, clubs must provide accurate pedigrees and ownership records, while also showing that the breed has been "breeding true" for several generations, that is, having two dogs of the same breed consistently producing offspring that are recognizable as that breed.
|
|
Foal inspections are also used to determine whether or not a stallion is producing offspring that fit the breeding goal.
|
|
It is possible that the nutrition deprived state of the parent cells before autogamy created a barrier for producing offspring that could thrive in those same stressful environments.
|
|
When beta males mate-guard a female, the competition between them allows the alpha males to have a greater chance of producing offspring, since betas outnumber alphas 21 to 1.
|
|
This species occurs with another member of its genus, Borrichia arborescens, in some parts of its range. The two often hybridize, producing offspring that has been called Borrichia × cubana, the Cuban borrichia.Borrichia × cubana. Integrated Taxonomic Information System.
|
|
He was retired to stud duty, producing offspring that have met with modest success. He stood at Diane Rochelle's Eagle Oak Ranch in Paso Robles, California, and died due to an apparent heart attack on the morning of May 18, 2010.
|
|
Many of the early colonists who migrated from England came with some or all of their family.Main, p. 29 It was expected that individuals would marry fairly young and begin producing offspring. Infant mortality rates were comparatively low, as were instances of childhood death.
|
|
Later Tamagotchi models have added a Senior model. Usually the pet's age will increase once it has awakened from its sleep time. Poor care can cause a pet to die, but it can also die of old age. If an old pet dies without producing offspring, the family line has ended.
|
|
Researchers concur that when the striped maple experiences damage or is sick, this will trigger a sex change to either female or female and male. This could be because the striped maple would need to bloom as quickly as possible, producing offspring before it ultimately dies from damage or sickness.
|
|
Thayer's kingsnake is a subspecies of the mexicana group of the genus Lampropeltis. Thayer's kingsnake is endemic to the eastern slopes of the Mexican plateaus in Tamaulipas, Mexico. Thayer's kingsnake is known for producing offspring typically displaying three main variable phases within the same clutch from similar-coloured patterned parents.Applegate, Bob.
|
|
Andre (as the Indian) greets him with "Who art thou, human creature?" The gallery is filled with people. The Indian is carried to where the people are, and they speculate that he can revive them by producing offspring with supreme qualities. However, the Indian says that he is sterile (much to their dismay).
|
|
The mechanisms of reproductive isolation are a collection of evolutionary mechanisms, behaviors and physiological processes critical for speciation. They prevent members of different species from producing offspring, or ensure that any offspring are sterile. These barriers maintain the integrity of a species by reducing gene flow between related species.Strickberger, M. 1978. Genética.
|
|
This species, like all the Naultinus species, is regarded as the Holy grail of Geckos among their keepers, often going for a large amount of money for a pair of lizards. Outside of its home range, it is most commonly kept in Europe where there are several keepers producing offspring, though still extremely rarely seen.
|
|
In some populations there are two kinds of females, one producing offspring in a normal 1:1 sex ratio, the other producing females only. In other populations the sex ratio is apparently normal. Scientists first believed the distorted sex-ratio was caused by a driving W chromosome. Later research suggests it is caused by cytoplasmic bacteria.
|
|
In addition to its very limited range, P. exserta is also threatened because it so easily hybridizes with other Petunia species in its native range, especially with Petunia axillaris, thus producing offspring that are hybrids rather than the species. The plant is increasingly being sold in horticulture, so the threat to its survival is only in its native habitat.
|
|
Glassworts, like other halophytes, can handle a wide range of temperatures and are evolved to handle sudden environmental changes. Producing offspring through clonal reproduction allows them to survive in conditions that are less than ideal . The preferred climate type is warm-temperate and subtropical regions . where they can easily reproduce through seeds to keep populations genetically stable.
|
|
In Greek mythology, Gaia (earth) bore six male and six female Titans to her son, Uranus (sky). The male Titans were Oceanus, Coeus, Crius, Hyperion, Lapeteus, and Cronus. The female Titans were Theia, Rhea, Themis, Mnemosyne, Phoebe, and Tethys. The male Titans each picked a female sibling for a wife and mated with them, producing offspring of their own.
|
|
Additionally the queen invests equally in each offspring, as it is unknown whether the larvae will be deemed an intermediate or queen until later on in adulthood. This means that the intermediates have the chance of producing offspring in the next colony along with other queens, and the queens have little to no control over this reproduction.
|
|
It is most abundant in coarse soils. Most individuals of the species are female and they reproduce by parthenogenesis, producing offspring without fertilization. They lay eggs in the soil and the juveniles feed on roots as they develop. The length of the life cycle varies with temperature, but it may be as short as 16 days.
|
|
A male donkey (jack) can be crossed with a female horse to produce a mule. A male horse can be crossed with a female donkey (jenny) to produce a hinny. Horse-donkey hybrids are almost always sterile because horses have 64 chromosomes whereas donkeys have 62, producing offspring with 63 chromosomes. Mules are much more common than hinnies.
|
|
When cells divide, their full genome is copied and each daughter cell inherits one copy. This process, called mitosis, is the simplest form of reproduction and is the basis for asexual reproduction. Asexual reproduction can also occur in multicellular organisms, producing offspring that inherit their genome from a single parent. Offspring that are genetically identical to their parents are called clones.
|
|
An isolating mechanism prevents members of two different species from successfully producing offspring. Dobzhansky invented the term, and in the eighth chapter he discusses their role in speciation. His views were sufficiently original for him to publish them in a journal article as well. Although previous authors had recognized the importance of isolation, their reasons were entirely different from his.
|
|
Infections of Wolbachia, a commonly infectious strain of bacteria observed in many insects such as Trichogramma and Muscidifurax uniraptor wasps, are transmitted between generations of Drosophila simulans. Wolbachia is inherited through maternal heredity. The infection is maintained through a process involving cytoplasmic incompatibility (CI) in which Wolbachia hinders uninfected individuals from producing offspring. Wolbachia has formed a symbiotic relationship with D. simulans.
|
|
One thing that stood out was that Python show little signs of "W-shrinking". Boa and Python families are now known to probably have an XY sex-determination system. Interest in looking into this came from female family members capable of parthenogenesis, or producing offspring without mating. In 2010 a female Boa constrictor that produced 22 female offspring in this manner was found in the wild.
|
|
The statue was an object of superstitious rites in Brittany for centuries. It was believed that sick people would be cured by touching the statue. Childless people would often pay a visit to the statue in the hope of producing offspring. It is said that during seventeenth century "foul", "indecent and obscene" rites were also practiced at the statue, and that many couples performed "erotic" acts near the statue.
|
|
These angels are cast down from the heaven after mistrusting Adam for his inclination towards sin.Michael Laitman, The Zohar Once in Earth, they complete the Enochian narrative by teaching magic to humans and producing offspring with them, as well as consorting with Lilith (hailed as "the sinner"). In the narrative, the Zohar affirms but simultaneously prohibits magical practices.Aryeh Wineman, Mystic Tales from the Zohar Princeton University Press p.
|
|
Stained human sperm Human spermatozoa Sperm competition is the competitive process between spermatozoa of two or more different males to fertilize the same egg during sexual reproduction. Competition can occur when females have multiple potential mating partners. Greater choice and variety of mates increases a female's chance to produce more viable offspring. However, multiple mates for a female means each individual male has decreased chances of producing offspring.
|
|
While some species of wasp select their queen on the basis of size, the selection of A. flavissima queens is physically pre-determined. Workers have under developed ovaries and are incapable of producing offspring throughout their entire lifestyle. Queens are the only females with developed ovaries and have long ovarioles with two or three mature oocytes. In contrast, worker A. flavissima exhibit underdeveloped ovaries with no visible oocytes.
|
|
From the earliest records, the ancient Sumerians had very relaxed attitudes toward sex and did not regard anal sex as taboo. Entu priestesses were forbidden from producing offspring and frequently engaged in anal sex as a method of birth control. Anal sex is also obliquely alluded to by a description of an omen in which a man "keeps saying to his wife: 'Bring your backside.'" Other Sumerian texts refer to homosexual anal intercourse.
|
|
The gemmules were dispersed around the organism and could multiply by division. In sexual reproduction they were transmitted from parents to their offspring with the mixing of the gemmules producing offspring with 'blended' characteristics of the parents. Gemmules could also remain dormant for several generations before becoming active. He also suggested that the environment might affect the gemmules in an organism and thus allowed for the possibility of the Lamarckian inheritance of acquired characteristics.
|
|
Based on Darwinian principles those that "out mate" others have a greater chance of successfully producing offspring. According to this theory, when there are differences in costs of errors made under conditions of uncertainty, selection favours "adaptive biases". Humans are animals, and evolution charts their passage from single celled organisms to the media and technology-consuming organisms of today. These adaption biases ensure that less costly survival or reproductive errors will be committed.
|
|
Male small heaths aggregate and form leks often around bushes or trees, creating an elaborate visual display to attract a female's attention. The female will approach by circling the lek, which attracts the males' attention more than being stationary. There are both costs and benefits of lekking for the female. Females benefit by typically mating with the dominant male and producing offspring with beneficial, heritable genes, as a result of their free choice in mates.
|
|
In an ancient Hawaiian myth, the cosmic couple who gave birth to the Hawaiian islands were a brother and his older sister. This became the basis for a custom called pi'o, intentional incestuous copulation within the upper class. Extensive genealogies were maintained in order to produce the most inbred (and thus, "powerful") chiefs possible. The commoners were forbidden to do this out of fear that they would begin producing offspring with chief-like levels of mana.
|
|
Demography, disease and the devil: life- history changes in a disease-affected population of Tasmanian devils (Sarcophilus harrisii). Journal of Animal Ecology ,78, 427-436. with most females now only having the opportunity to breed once rather than typically producing offspring annually for 3 years after the age of two. The loss of Tasmanian devils also places other species within Freycinet National Park at risk, as the decline of such a predator could alter interactions between other species.
|
|
The Sifthei Kohen (vol. 2 p. 244) commentary to the Torah points out that the kohen personality is to be extra-scrupulous with oral-vulvar stimulation of his wife when producing offspring, as per Rabbi Yochanan's ben Dhabai's warning that it may cause a physical blemish were his wife to conceive; as a kohen is bounded by the Torah rules of kohanic disqualifications, and may be disqualified from specific Bet HaMikdash services if he has a physical blemish.
|
|
During that period, a handful of ranchers gathered remnants of the existing herds to save the species from extinction. These ranchers bred some of the bison with cattle in an effort to produce "cattleo" (today called "beefalo") Accidental crossings were also known to occur. Generally, male domestic bulls were crossed with buffalo cows, producing offspring of which only the females were fertile. The crossbred animals did not demonstrate any form of hybrid vigor, so the practice was abandoned.
|
|
The proletariat ( from Latin "producing offspring") is the social class of wage-earners, those members of a society whose only possession of significant economic value is their labour power (their capacity to work).proletariat. Accessed: 6 June 2013. A member of such a class is a proletarian. Marxist philosophy considers the proletariat to be oppressed by capitalism, forced to accept meager wages in return for operating the means of production, which belong to the class of business owners, the bourgeoisie.
|
|
Generally, male domestic bulls were crossed with buffalo cows, producing offspring of which only the females were fertile. The crossbred animals did not demonstrate any form of hybrid vigor, so the practice was abandoned. The proportion of cattle DNA that has been measured in introgressed individuals and bison herds today is typically quite low, ranging from 0.56 to 1.8%. In the United States, many ranchers are now using DNA testing to cull the residual cattle genetics from their bison herds.
|
|
The scientists fear she may mate with human males and produce offspring that could eliminate the human race. Sil is intent on producing offspring as soon as possible, and kills several people to prevent them from notifying the authorities or simply to use their clothing. Sil first tries to mate with Robbie (Anthony Guidera), but after sensing that he is diabetic, she rejects him. Unsatisfied, he tries to rape her, prompting her to kill him by puncturing his skull with her tongue.
|
|
In asexual organisms, genes are inherited together, or linked, as they cannot mix with genes of other organisms during reproduction. In contrast, the offspring of sexual organisms contain random mixtures of their parents' chromosomes that are produced through independent assortment. In a related process called homologous recombination, sexual organisms exchange DNA between two matching chromosomes. Recombination and reassortment do not alter allele frequencies, but instead change which alleles are associated with each other, producing offspring with new combinations of alleles.
|
|
The lizards that hatch from these eggs are thus also parthenogens that can again produce identical eggs, resulting in an asexual, clonal population. Parthenogenetic species resulting from a single hybridization are diploid (that is, they have two sets of chromosomes just as sexual species do), but sometimes these females mate with other males, producing offspring which are triploid (that is, they have three sets of chromosomes, or 50% more than equivalent sexual species; see polyploidy). Over 30% of the genus Cnemidophorus are parthenogenic.
|
|
In mathematical genetics, a genetic algebra is a (possibly non-associative) algebra used to model inheritance in genetics. Some variations of these algebras are called train algebras, special train algebras, gametic algebras, Bernstein algebras, copular algebras, zygotic algebras, and baric algebras (also called weighted algebra). The study of these algebras was started by . In applications to genetics, these algebras often have a basis corresponding to the genetically different gametes, and the structure constant of the algebra encode the probabilities of producing offspring of various types.
|
|
Crosses between different species of Cochliobolus are possible, producing offspring differing in conidial morphology. Horizontal and vertical gene transfer has occurred within and between fungal species of Cochliobolus and might be the reason for occurrence of highly virulent, toxin producing races of C. heterostrophus, C. carbonum and C. victoriae.Turgeon, B.G. and M. Berbee, Evolution of pathogenic and reproductive strategies in Cochliobolus and related genera, in Molecular Genetics of Host-Specific Toxins in Plant Disease, K. Kohmoto and O. Yoder, Editors. 1998, Springer Netherlands. p. 153-163.
|
|
Merriam's kangaroo rats breed between February and May and produce two or three litters per year. Before mating, the male and female will perform nasal-anal circling until the female stops and allows the male to mount her. A Merriam's kangaroo rat female will allow multiple males to mount her in a short time, perhaps to ensure greater chances of producing offspring. Mating in banner-tailed kangaroo rats involves more chasing and foot drumming in the male before the female allows him to mate.
|
|
Females often parasitize their own species, either stealing prey from nests of other females to provision their own nests, or in brood parasitism, removing the other female's egg and laying one of her own instead. Brood parasitism "appears to be a cheap and easy route to producing offspring", as it takes only about 30 minutes to switch eggs in an existing nest, but about 10 hours to build and provision a new nest; however, more than 80% of brood-parasitized nests were themselves parasitized by another female.
|
|
The sphragis acts to increase the chance of individual males successfully producing offspring by preventing other males from inseminating already mated females. There is evidence that females have attempted to counter this strategy by evolving remarkably broad genitalia that makes it more difficult for sphragides to remain in place. The evolutionary incentive to counter the sphragis is likely the nutritional benefit females obtain from the spermatophore, hence multiple matings provide female butterflies with additional resources. The sphragis does not obstruct the passage of eggs as there are separate orifices for copulation and oviposition.
|
|
Benefits for helpers include a reduced chance of predation, increased foraging time, territory inheritance, increased environmental conditions and an inclusive fitness. Inclusive fitness is the sum of all direct and indirect fitness, where direct fitness is defined as the amount of fitness gained through producing offspring. Indirect fitness is defined as the amount of fitness gained through aiding related individuals offspring, that is relatives are able to indirectly pass on their genes through increasing the fitness of related offspring.Nicholas B. Davies, John R. Krebs, S. A. W. An Introduction to Behavioural Ecology.pdf.
|
|
Because of the curse, they have forgotten their original form and are incapable of producing offspring due to this fact. ;Mist Dragon - Troll :Its appearance is similar to that of a rhinoceros carrying what appears to be a tower on its back. Their bodies are extremely durable, and their skin can even withstand the temperature of lava. It can generate bullets from its body by consuming rock and metal, which can ejected from the numerous "barrels" on its back, and the power of a single bullet is enough to destroy a steel ship.
|
|
Philopatric species that do not migrate may evolve to breed cooperatively. Kin selection, of which cooperative breeding is a form, explains how individual offspring provide care for further offspring produced by their relatives. Animals that are philopatric to birthsites have increased association with family members, and, in situations where inclusive fitness is increased through cooperative breeding, may evolve such behaviour, as it will incur evolutionary benefits to families that do. Inclusive fitness is the sum of all direct and indirect fitness, where direct fitness is defined as the amount of fitness gained through producing offspring.
|
|
T. angustula is a very small bee and builds unobtrusive nests, allowing it to thrive in urban areas. It also produces large amounts of honey, and is thus frequently kept in wooden hives by beekeepers. T. angustula hives are often overlooked, and since the bee lacks a stinger, it is not seen as a threat to humans. alt= Many of their behaviors are concerned with colonizing a new nest and producing offspring, demonstrated by their swarming and nursing behaviors, however a special caste of T. angustula are soldiers who are slightly larger than the workers.
|
|
From the point of view of animal and plant breeders, there are several kinds of hybrid formed from crosses within a species, such as between different breeds. Single cross hybrids result from the cross between two true-breeding organisms which produces an F1 hybrid (first filial generation). The cross between two different homozygous lines produces an F1 hybrid that is heterozygous; having two alleles, one contributed by each parent and typically one is dominant and the other recessive. Typically, the F1 generation is also phenotypically homogeneous, producing offspring that are all similar to each other.
|
|
Project Golden Frog is a conservation project involving scientific, educational, and zoological institutions in the Republic of Panama and the United States. The intended outcomes of this project include a greater understanding of the Panamanian golden frog, a coordinated conservation effort by governmental agencies and nongovernmental organizations, heightened awareness of current global amphibian declines, greater respect for wildlife among Panamanians and global citizens, and greater land preservation for threatened and endangered species throughout the world. This organization will use education and field studies, producing offspring through the already captive toads, and offering financial support to help preserve these toads.The Conservation Initiative. Ranadorada.
|
|
Some animals are capable of mating, producing offspring that may be capable of being raised as a mount or battle pet, though the chances of this happening are extremely rare. Players may choose to uproot plants or needlessly slaughter animals before they are fully matured. Doing so will result in the removal of the plant or animal and has a chance to yield a small return, though typically will result in a loss of the initial item. As with housing, farms require a tax to be paid in order to maintain ownership of the plots upon which they are placed.
|
|
The shark ray breeding program is one of the first of its kind and much is being learned about shark rays. It has been successful, with "Sweet Pea" and "Scooter" producing offspring. However, the process is difficult due to the tendencies of shark rays to have "rough sex," which caused one of the new females, at the time, to be killed. The aquarium has a total of four adult shark rays on exhibit today and scientists have been able to learn more about their reproductive behaviors and gestation periods, which is being used to better care for them.
|
|
Competitiveness despite parental investment has also been observed in some species. A related factor is the rate at which males and females are able to mate again after producing offspring, and the basic principles of sexual selection are also influenced by ecological factors affecting the ways or extent to which one sex can compete for the other. The role of such factors in human evolution is controversial. The pattern of male and female aggression is argued to be consistent with evolved sexually-selected behavioral differences, while alternative or complementary views emphasize conventional social roles stemming from physical evolved differences.
|
|
There is general agreement that copulatory calls are the adaptive solution to problems with reproductive success. In other words, copulatory vocalizations address issues that stand in the way of successfully producing offspring and guaranteeing its survival, such as the occurrence of infanticide. To prevent the killing of their offspring, female baboons employ copulatory calls in order to attract other males, allowing multiple mating acts and creating parental confusion among the males involved. The resulting uncertainty of who the father is hence reduces the occurrence of attacks, given the newly incited risk of potentially harming their own offspring.
|
|
The Prince Regent was estranged from his wife, who was 49 years old, thus there was little likelihood that he would have any further legitimate children. To secure the line of succession, Prince William, Duke of Clarence, and the other sons of George III sought quick marriages with the intent of producing offspring who could inherit the throne. William already had ten children by the popular actress Dorothea Jordan, but, being illegitimate, they were barred from the succession. Considerable allowances were likely to be voted by Parliament to any royal duke who married, and this acted as a further incentive for William to marry.
|
|
Concerning Goldberg's claims about the "feelings of both men and women", Eleanor Leacock countered in 1974 that the data on women's attitudes are "sparse and contradictory", and that the data on male attitudes about male–female relations are "ambiguous". Also, the effects of colonialism on the cultures represented in the studies were not considered. An early theory in evolutionary psychology offered an explanation for the origin of patriarchy which starts with the view that females almost always invest more energy into producing offspring than males, and therefore in most species females are a limiting factor over which males will compete. This is sometimes referred to as Bateman's principle.
|
|
For example, helping a sibling (in diploid animals) has a coefficient of , because (on average) an individual shares half of the alleles in its sibling's offspring. Ensuring that enough of a sibling's offspring survive to adulthood precludes the necessity of the altruistic individual producing offspring. The coefficient values depend heavily on the scope of the playing field; for example if the choice of whom to favor includes all genetic living things, not just all relatives, we assume the discrepancy between all humans only accounts for approximately 1% of the diversity in the playing field, a coefficient that was in the smaller field becomes 0.995. Similarly if it is considered that information other than that of a genetic nature (e.g.
|
|
Given the demands of fetal loading during pregnancy and the importance of producing offspring to the fitness of human beings, one can imagine that natural selection has had a role in selecting a unique anatomy for the lumbar region in females. It turns out that there are sex differences in the lumbar vertebral column of human males and females, which ultimately helps mitigate some of the discomfort due to the fetal load in females. There are 5 vertebrae in the lumbar region for both males and females. However, the 3 lower vertebrae of a female's lumbar region are dorsally wedged while for males, only the lower 2 of the lumbar region are dorsally wedged.
|
|
When, after the death of his father on 28 September 1574, Francesco Maria II della Rovere became the new Duke of Urbino, Lucrezia became in the Duchess consort of Urbino. Her relationship with her younger husband has always been difficult: without hesitation, the Duke pointed out that the failure of producing offspring was only Lucrezia's fault due to her old age, despite the fact that he himself infected her with syphilis. During these years, Lucrezia found a great source of consolation in her friendship with Torquato Tasso, who was on duty at the Duchess's court in Pesaro and Urbania. After eight years of marriage, and through the mediation of Cardinal Carlo Borromeo, the Ducal couple of Urbine were finally able to obtain a separation.
|
|
Hybrid sterility can be caused by different closely related species breeding and producing offspring, these animals are usually sterile due to different numbers of chromosomes from the two parents, causing an imbalance in the resulting offspring making it viable but not fertile, this is the case with the mule. Sterility can also be caused by selective breeding, where a selected trait is closely linked to genes involved in sex determination or fertility, for example goats breed to be polled (hornless), this results in a high number of intersex individuals among the offspring, which are typically sterile. Sterility can also be caused by chromosomal differences within an individual, these individuals tend to be known as a genetic mosaics. Loss of part of a chromosome can also cause sterility due to nondisjunction.
|
|
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.
|
|
Under such circumstances, the female has been known to respond with a defensive deimatic display by flashing the colored eyespots on the inside of her front legs. The reason for sexual cannibalism has been debated; experiments show that females on poor diets are likelier to engage in sexual cannibalism than those on good diets. Some hypothesize that submissive males gain a selective advantage by producing offspring; this is supported by a quantifiable increase in the duration of copulation among males which are cannibalized, in some cases doubling both the duration and the chance of fertilization. This is contrasted by a study where males were seen to approach hungry females with more caution, and were shown to remain mounted on hungry females for a longer time, indicating that males that actively avoid cannibalism may mate with multiple females.
|
|
The handicap principle has proven hard to test empirically, partly because of inconsistent interpretations of Zahavi's metaphor and Grafen's marginal fitness model, and partly because of conflicting empirical results: in some studies individuals with bigger signals seem to pay higher costs, in other studies they seem to be paying lower costs. A possible explanation for the inconsistent empirical results is given in a series of papers by Getty, who shows that Grafen's proof of the handicap principle is based on the critical simplifying assumption that signallers trade off costs for benefits in an additive fashion, the way humans invest money to increase income in the same currency. But the assumption that costs and benefits trade off in an additive fashion is true only on a logarithmic scale; for the survival cost – reproduction benefit tradeoff is assumed to mediate the evolution of sexually selected signals. Fitness depends on producing offspring, which is a multiplicative function of reproductive success given an individual is still alive times the probability of still being alive, given investment in signals.
|
|
Estrus evolved to facilitate reproduction and maximize reproductive success, or the success of passing on one's genes by producing offspring that are most likely to survive and reproduce themselves. The ovulatory shift hypothesis proposes that motivation and desire to mate should increase during the fertile window, and that females should seek and attract the best possible mate at their highest fertility. An ideal mate could have many qualities: resources to care for offspring, the physical ability and social status to protect a mate and offspring, a compatible personality for a long-term pair bond, etc. Evolutionary theory and sexual selection theory suggest that an organism’s top priority should be to maximize survival and reproductive success. Thus, the ovulatory shift hypothesis proposes that women possess a dual sexuality, where during the fertile window, a woman should prioritize attracting and choosing a mate with the best genetic quality, or “good genes”, since this is the only time she can become pregnant and pass on heritable genetic qualities to her offspring.
|
|