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Orestias (fish)
''Orestias'' is a genus of pupfish. Older systematics classified them into the own family Orestiidae. They are carnivorous plankton feeders and can reach a length between . Their most characteristic feature is the absence of the ventral fin. They are endemic to freshwater habitats in the Andean highlands in Peru, Bolivia, and Chile. The majority of the species are endemic to Lake Titicaca (Maldonado et al. gives only 15 species—i.e., not a majority—endemic to the lake), but some species are from other Altiplano lakes or rivers. Many species of the genus became rare in recent decades due to competition with introduced fish species, pollution, and human activities at the lakes. One species—the Titicaca Orestias (''Orestias cuvieri'')—was last seen in 1939 and is probably extinct; several others are known to have highly restricted ranges (Parenti 1984). Several species are colloquially known as ''carache''.
==Species==
There are currently 45 recognized species in this genus, divided by American ichthyologist Lynne R. Parenti in 1984 depending on their relationships into four species complexes. The genus is estimated to be 5 million years old, with a significant diversification occurring within the last one million years. Lüssen (2003) researched the phylogeny of several species including mtDNA sequence data; because hybridization is known to occur (Villwock 1964, Parenti 1984), mtDNA data cannot be relied upon on its own to resolve the evolution of this genus.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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