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The pygmy marmoset (''Cebuella pygmaea'') is a small New World monkey native to rainforests of the western Amazon Basin in South America. It is notable for being the smallest monkey and one of the smallest primates in the world at just over (Madame Berthe's mouse lemur is smaller). It is generally found in evergreen and river edge forests and is a gum-feeding specialist. About 83% of the pygmy marmoset population lives in stable troops of two to nine individuals, including a dominant male, a breeding female, and up to four successive litters of offspring. The modal size of a standard stable troop would be 6 individuals.〔Soini, Pekka. "Ecology and Population Dynamics of the Pygmy Marmoset, Cebuella Pygmaea." Folia Primatologica 39.1-2 (1982): 1-21. Print.〕 Although most groups consist of family members, some may also include 1-2 additional adult members. Members of the group communicate using a complex system including vocal, chemical, and visual signals. There are three main calling signals that depend on the distance the call needs to travel. These monkeys may also make visual displays when threatened or to show dominance. Chemical signaling using secretions from glands on the chest and genital area allow the female to indicate to the male when she is able to reproduce. The female gives birth to twins twice a year and the parental care is shared between the group. The pygmy marmoset has been viewed as somewhat different from typical marmosets, most of which are classified in the genera ''Callithrix'' and ''Mico'', and thus is accorded its own genus, ''Cebuella'', within the family Callitrichidae. It is listed as Least Concern by the International Union for Conservation of Nature as it is common across its wide range and not at immediate risk of widespread decline. The biggest threats to the species are habitat loss and the pet trade.〔Stella de la Torre, Charles T Snowdon, Monserrat Bejarano, Effects of human activities on wild pygmy marmosets in Ecuadorian Amazonia, Biological Conservation, Volume 94, Issue 2, July 2000, Pages 153-163, , 〕 == Evolution and taxonomy == There has been debate among primatologists concerning the proper genus in which to place the pygmy marmoset. An examination of the interstitial retinol binding protein nuclear gene (IRBP) in three marmoset species showed that ''Callithrix'' as constructed in the 1990s also needed to include ''C. pygmaea'' to be monophyletic, and that the times of separation of ''pygmaea'' and the ''argentata'' and ''jacchus'' species groups from one another are less than 5 million years ago, as might be expected for species of the same genus. However, subsequent separation of the ''argentata'' and ''jacchus'' species groups into different genera (the ''argentata'' group having been moved to ''Mico'') justifies maintaining a separate genus for the pygmy marmoset, as ''Callithrix'' is no longer paraphyletic.〔 There are two subspecies described by Colin Groves of the pygmy marmoset:〔〔 *''Cebuella pygmaea pygmaea'' – Northern/Western pygmy marmoset *''Cebuella pygmaea niveiventris'' – Eastern pygmy marmoset There are few morphological differences between these subspecies, as they may only differ slightly in color, and they are only separated by geographical barriers, including large rivers in Central and South America. The evolution of this species diverged in terms of body-mass from typical primates, with a high rate of body-mass reduction. This involves large decreases in pre-natal and post-natal growth rates, furthering the thought that pro-genesis played a role in the evolution of this animal.〔Montgomery, S. H. and Mundy, N. I. (2013), Parallel episodes of phyletic dwarfism in callitrichid and cheirogaleid primates. Journal of Evolutionary Biology, 26: 810–819. 〕 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「Pygmy marmoset」の詳細全文を読む スポンサード リンク
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