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The impala (''Aepyceros melampus'') is a medium-sized African antelope. It is the type species of the genus ''Aepyceros'' and belongs to the family Bovidae. It was first described by German zoologist Martin Hinrich Carl Lichtenstein in 1812. Two subspecies of the impala have been recognised: the common impala (''A. m. melampus'') and the black-faced (''A. m. petersi''). They are typically between long. Males stand up to approximately at the shoulder and weigh , while females are and . Both are characterised by a glossy, reddish brown coat. Only the males have the characteristic slender, lyre-shaped horns, which can grow to be long. The impala inhabits savanna grasslands and woodlands in close proximity to water sources. It is a mixed forager, whose diet consists of grasses, forbs, monocots, dicots and foliage. It switches between grazing and browsing depending on the season and habitat. Water is an essential requirement. Impala are fast runners and are known for their leaping ability, reaching heights up to . They communicate using a variety of unique visual and vocal cues. There are three distinct social groups during the wet season: the female herds, the bachelor herds and the territorial males. The mating season is the three-week-long period toward the end of the wet season in May. A single fawn is born after a gestational period of about six to seven months. The fawn remains with its mother for four to six months, after which it joins juvenile groups. The impala is native to Angola, Botswana, Kenya, Malawi, Mozambique, Namibia, Rwanda, South Africa, Swaziland, Tanzania, Uganda, Zambia and Zimbabwe. Regionally extinct in Burundi, it has been introduced in two protected areas of Gabon. The black-faced impala is confined to Kaokoland (Namibia) and southwestern Angola. The common impala has been widely introduced in southern Africa. Though there are no major threats to the survival of the species as a whole, poaching and natural calamities have significantly contributed to the decline of the black-faced subspecies. While the common impala has been listed as of Least Concern by the International Union for Conservation of Nature (IUCN), the black-faced has been rated as Vulnerable. ==Etymology and taxonomy== The scientific name of the impala is ''Aepyceros melampus''. It is the type species of the genus ''Aepyceros'' and belongs to the family Bovidae. It was first described by German zoologist Martin Hinrich Carl Lichtenstein in 1812.〔 The vernacular name "impala" comes from the Zulu language meaning "gazelle". The scientific name is derived from Greek words αιπος ''aipos'' ("high"), κερος ''ceros'' ("horn") and ''melas'' ("black"), ''pous'' ("foot").〔 Due to its close affinity to some species of gazelles, the kob and reedbucks, taxonomists had placed the impala in the same tribe as these alcelaphines. Its resemblance to the hartebeest led palaeontologist Elisabeth Vrba to consider the impala as a sister clade to the alcelaphines, and ''Aepyceros'' was included under subfamily Alcelaphinae in 1985.〔 However, the impala was subsequently placed in its own tribe, Aepycerotini, in 1992, which has been elevated to subfamily status.〔 An rRNA and β-spectrin nuclear sequence analysis supported an association between ''Aepyceros'' and ''Neotragus''. Up to six subspecies have been described, although only two are usually recognised, supported by mitochondrial DNA analysis. These are the common (''A. m. melampus'') and the black-faced (''A. m. petersi'') impala. While the former is abundant throughout southern and eastern Africa, the latter is restricted to southwestern Africa. Both subspecies show much genetic differentiation, and no hybrids are known. Several fossil species have been found, including ''A. datoadeni'' from the Pliocene of Ethiopia. A study by Vrba revealed that while the common alcelaphine ancestor has diverged at least 18 times into various morphologically different forms of hartebeest and wildebeest, the impala has continued in its basic form for at least five million years. The oldest fossil discovered suggests its ancient ancestors were slightly smaller than the modern form, but otherwise similar in all respects to the latter. Even the two subspecies have only a few differences between them. This implies that the impala is very well adapted to its environment. Its gregarious nature, variety in diet, high population growth, defence against ticks and cooperation with oxpeckers who feed on ticks are some of the traits suggested as preventing major changes in morphology and behaviour.〔 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「impala」の詳細全文を読む スポンサード リンク
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