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''Capra'' is a genus of mammals, the goats or wild goats, composed of up to nine species, including the wild goat, the markhor, and several species known as ibex. The domestic goat (''Capra aegagrus hircus'') is a domesticated subspecies of the wild goat (''Capra aegagrus''). Evidence of goat domestication dates back more than 8,500 years. Wild goats are animals of mountain habitats. They are very agile and hardy, able to climb on bare rock and survive on sparse vegetation. They can be distinguished from the genus ''Ovis'', which includes sheep, by the presence of scent glands close to the feet, in the groin, and in front of the eyes, and the absence of other facial glands, and by the presence of a beard in the males, and of hairless calluses on the knees of the forelegs. The Rocky Mountain goat is in a separate genus, ''Oreamnos''. ==Taxonomy== All members of the ''Capra'' genus are bovids (members of the family Bovidae) and caprids (subfamily Caprinae). All these are ruminants, meaning they chew the cud, and have four-chambered stomachs which play a vital role in digesting, regurgitating, and redigesting their food. The genus has sometimes been taken to include ''Ovis'' (sheep) and ''Ammotragus'' (Barbary sheep),〔Ansell, W. F. H. 1972. Order Artiodactyla. Part 15. Pp. 1–84, in ''The mammals of Africa: An identification manual'' (J. Meester and H. W. Setzer, eds.) (2 May 1972 ). Smithsonian Institution Press, Washington, D.C., not continuously paginated. (quoted in )〕 but these are usually regarded as distinct genera, leaving ''Capra'' for goats and ibexes. In this smaller genus, some authors have recognized only two species, the markhor on one side and all other forms included in one species on the other side.〔Haltenorth, T. 1963. Klassifikation der Säugetiere: Artiodactyla I. ''Handbuch der Zoologie'', 8(32):1–167 (quoted in )〕 Today, nine species are usually accepted:〔Nathalie Pidancier, Steve Jordan, Gordon Luikart, Pierre Taberlet: Evolutionary history of the genus Capra (Mammalia, Artiodactyla): Discordance between mitochondrial DNA and Y-chromosome. Molecular Phylogenetics and Evolution 40 (2006) 739–749 (online )〕 * West Caucasian tur (''Capra caucasica'') * * East Caucasian tur (''Capra caucasica cylindricornis'') * Markhor (''Capra falconeri'') * Domestic goat (''Capra hircus''; includes feral goat) * * Bezoar ibex (''Capra hircus aegagrus'') * Alpine ibex (''Capra ibex'') * Nubian ibex (''Capra nubiana'') * Spanish ibex (''Capra pyrenaica'') * Siberian ibex (''Capra sibirica'') * Walia ibex (''Capra walie'') The goats of the genus ''Capra'' have complex systematic relationships, which are still not completely resolved. Recent studies based on mitochondrial DNA suggest that the Siberian ibex and the Nubian ibex represent distinct species, which are not very closely related to the physically similar Alpine ibex. The Alpine ibex forms a group with the Spanish ibex. The West Caucasian tur appears to be more closely related to the wild goat than to the East Caucasian tur. The markhor is relatively little separated from other forms—previously it had been considered to be a separate branch of the genus.〔''Phylogenetic Reconstructions in the Genus Capra (Bovidae, Artiodactyla) Based on the Mitochondrial DNA Analysis''. Russian Journal of Genetics, 2007, Vol. 43, No. 2, pp. 181–189. (online )〕 Almost all wild goat species are allopatric (geographically separated)—the only geographical overlaps are the wild goat (''Capra hircus'') with the East Caucasian tur (''Capra caucasica cylindricornis''), and the markhor (''Capra falconeri'') with the Siberian ibex (''Capra siberica''). In both cases, the overlapping species do not usually interbreed in the wild, but in captivity, all ''Capra'' species can interbreed, producing fertile offspring.〔V. G. Heptner: ''Mammals of the Sowjetunion Vol. I UNGULATES''. Leiden, New York, 1989 ISBN 90-04-08874-1〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Capra (genus)」の詳細全文を読む スポンサード リンク
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