|
The Olympic marmot (''Marmota olympus'') is a rodent in the squirrel family Sciuridae; it occurs only in the U.S. state of Washington, on the middle elevations of the Olympic Peninsula. The closest relatives of this species are the hoary marmot and the Vancouver Island marmot. In 2009, it was declared the official endemic mammal of Washington. This marmot is about the size of a domestic cat, typically weighing about in summer. The species shows the greatest sexual dimorphism found in marmots, with adult males weighing on average 23% more than females. It can be identified by a wide head, small eyes and ears, stubby legs, and a long, bushy tail. Its sharp, rounded claws aid in digging burrows. The coat color changes with the season and with age, but an adult marmot's coat is brown all over with small whiter areas for most of the year. The Olympic marmot has a diet consisting mainly of a variety of meadow flora, including dry grasses, which it also uses as bedding in burrows. It is preyed on by various terrestrial mammals and avian raptors, but its main predator today is the coyote. The Olympic marmot is rated a species of the least concern on the IUCN Red List. It is protected by law in the Olympic National Park, which contains most of its habitat. The burrows of this marmot are made in colonies, which are found in various mountain locations and differ in size. A colony may contain as few as one marmot family or multiple families with up to 40 marmots. Olympic marmots are very sociable animals which often engage in play fighting and vocalize four different whistles to communicate. During hibernation beginning in September, they are in a deep sleep and do not eat, causing them to lose half their body mass. Adults emerge in May and their young in June. Female marmots reach sexual maturity at three years of age, and produce litters of 1–6 every other mating season. == Taxonomy == American zoologist and ethnographer Clinton Hart Merriam first formally described the Olympic marmot in 1898, as ''Arctomys olympus'', from a specimen he and Vernon Orlando Bailey collected on the Sol Duc River. The species name ''olympus'' (Olympic in Greek) was given because this species is native to the Olympic Peninsula.〔 The species now is classified with all other marmots in the genus ''Marmota''. Zoologist R. L. Rausch classified the Olympic marmot as the subspecies ''olympus'' of ''Marmota marmota'' (he included all North American marmots in this species, which now only includes the Eurasian Alpine marmot) in 1953, but it has usually been treated as a distinct species, a classification supported by taxonomic reviews starting with that of zoologist Robert S. Hoffmann and colleagues in 1979.〔 Within ''Marmota'', the Olympic marmot is grouped with species such as the hoary marmot (''M. caligata'') in the subgenus ''Petromarmota''. Among this grouping, mitochondrial DNA analyses suggest that the Olympic marmot could be the most basal species. The Olympic marmot is thought to have originated during the last glacial period as an isolated relict population of the hoary marmot in the Pleistocene ice-free refugia.〔 The Olympic marmot deviates from the typical ''Petromarmota'' marmots in the shape and large size of its mandible (jawbone), in differences of the dorsal (back) region, and having 40 chromosomes instead of 42, all of which are characteristics that resemble the subgenus ''Marmota''. Some of the differences of the Olympic marmot's jawbone from the typical ''Petramarmota'' are also evident in the Vancouver Island marmot (''M. vancouverensis''), which evolved separately, but also occurs in a restricted range with a small population. 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「Olympic marmot」の詳細全文を読む スポンサード リンク
|