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A rare species is a group of organisms that are very uncommon, scarce, or infrequently encountered. This designation may be applied to either a plant or animal taxon, and may be distinct from the term ''endangered'' or ''threatened species.'' Designation of a rare species may be made by an official body, such as a national government, state, or province. However, the term more commonly appears without reference to specific criteria. The IUCN does not normally make such designations, but may use the term in scientific discussion.〔(Categories & Criteria (version 3.1) IUCN, 2001. )〕 Rarity rests on a specific species being represented by a small number of organisms worldwide, usually fewer than 10,000. However, a species having a very narrow endemic range or fragmented habitat also influences the concept.〔R.MacNally and G.W.Brown, ''Reptiles and Habitat Fragmentation in the Box-ironbush Forests of Central Victoria, Australia: Predicting Compositional Change and Faunal Nested-ness'', Oecologia 128:116-125 (2001)〕 Rare species are not uncommon, since nearly 75% of known species are rare.〔Dinerstein, Eric (2013) (''The Kingdom of Rarities'' ) Island Press. ISBN 9781610911955.〕 A species may be endangered or vulnerable, but not considered rare if—for example—it has a large, dispersed population, but its numbers are declining rapidly or predicted to do so. Rare species are generally considered threatened because a small population size is more likely to not recover from stochastic events (things that ''could'' happen). Rare species are species with small populations. Many move into the endangered or vulnerable category if the negative factors affecting them continue to operate. Examples of rare species are the Himalayan brown deer, desert fox, wild Asiatic buffalo and hornbill. A rare plant's legal status can be observed through the USDA's (Plants Database ) ==See also== *Abundance (ecology) *Biodiversity Action Plan *''Chelonoidis nigra abingdonii'' *Common species *Critical depensation *Endangered Species Recovery Plan * Rare Species Conservation Centre 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「rare species」の詳細全文を読む スポンサード リンク
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