Neanderthals, as a discrete species, disappeared from the fossil record sometime between 41,000 and 39,000 years ago.
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During the nation's bicentennial, scientists determined that the giant hooded tortoise was a discrete species in need of saving, and Diego was returned to his native land, ready to get busy.
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But if tabulating untruths seems Sisyphean, at least we can catalogue them, the same way lepidopterologists catalogue butterflies—each wrong statement may be beautiful or perplexing in its own way, but if we pin them down under glass we can sort them out into a few discrete species.
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The taxonomy is complex, since it is a variable population. It is placed in subgenus Eriostemones, one of four subgenera of Tulipa. The species has at various times been treated as a variable taxon with a range of forms, divided into subspecies, including T. o. whittalii, or as a number of different discrete species, including T. bithynica, T. hageri and T. whittallii.
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It has been demonstrated that interbreeding happened in several independent events that included Neanderthals, Denisovans, as well as several unidentified hominins. Today, approximately 2% of DNA from most Eurasians is Neanderthal, with traces of Denisovan heritage. Also, 4-6% of the genome of modern Melanesian people is Denisovan. Denny represents the first time an ancient individual was discovered whose parents belonged to two discrete species of humans, meaning a 50/50 hybrid, which allows for extensive comparative genetic studies.
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When a loricariid receives an official scientific name, the L-number (or numbers) is retired; best practice is then to use the scientific name. A specific L-number classification does not guarantee a discrete species, multiple L numbers have been given to different populations of the same species. To add to the confusion, sometimes a single L-number may be used for multiple species. Additionally the aquarium magazine 'Das Aquarium' introduced a similar system using the prefix 'LDA'.
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It appears in William of Sherwood's Introduction to Logic and is given the name arbor Porphyrii in the most popular medieval logic, Peter of Spain's Summulae Logicales.Franklin's note: "N. Kretzmann, William of Sherwood's Introduction to Logic (Minneapolis: University of Minnesota Press, 1966), 54; Peter of Spain, Summulae Logicales, I. M. Bocheński (ed.) (Turin: Marietti, 1947), 17-18." Linnaeus's system of static and discrete species was simply the result of filling in the abstract Tree with the names of actual species.
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The zoologist Ludwig Döderlein first identified, described, and classified the frilled shark as a discrete species of shark. After three years (1879–1881) of marine research in Japan, Döderlein took two specimen sharks to Vienna, but lost the taxonomic manuscript of the research. Three years later, in the Bulletin of the Essex Institute (vol. XVI, 1884) the zoologist Samuel Garman published the first taxonomy of the frilled shark, based upon his observations, measurements, and descriptions of a –long female shark from Sagami Bay, Japan. In the article “An Extraordinary Shark” Garman classified the new species of shark within its own genus and family, and named it Chlamydoselachus anguineus (eel-like shark with frills).
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Other reasons such as gene flow interruption from "vicariate divergence" and fragmented populations due to climate instability have also been cited. Ring species also present an interesting case of the species problem for those seeking to divide the living world into discrete species. All that distinguishes a ring species from two separate species is the existence of the connecting populations; if enough of the connecting populations within the ring perish to sever the breeding connection then the ring species' distal populations will be recognized as two distinct species. The problem is whether to quantify the whole ring as a single species (despite the fact that not all individuals interbreed) or to classify each population as a distinct species (despite the fact that it interbreeds with its near neighbours).
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The extended wording on the title page, which adds by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life, uses the general terminology of biological races as an alternative for "varieties" and does not carry the modern connotation of human races. In The Descent of Man, and Selection in Relation to Sex (1871), Darwin examined the question of "Arguments in favour of, and opposed to, ranking the so-called races of man as distinct species" and reported no racial distinctions that would indicate that human races are discrete species."It may be doubted whether any character can be named which is distinctive of a race and is constant... they graduate into each other, and.. it is hardly possible to discover clear distinctive characters between them... As it is improbable that the numerous and unimportant points of resemblance between the several races of man in bodily structure and mental faculties (I do not here refer to similar customs) should all have been independently acquired, they must have been inherited from progenitors who had these same characters.", Charles Darwin, The Descent of Man p.
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