<P> If the population is panmixic, then Geospiza conirostris exhibits a balanced genetic polymorphism and not, as originally supposed, a case of nascent sympatric speciation . The selection maintaining the polymorphism maximises the species' niche by expanding its feeding opportunity . The genetics of this situation cannot be clarified in the absence of a detailed breeding program, but two loci with linkage disequilibrium is a possibility . </P> <P> Another interesting dimorphism is for the bills of young finches, which are either' pink' or' yellow' . All species of Darwin's finches exhibit this morphism, which lasts for two months . No interpretation of this phenomenon is known . </P> <P> For some decades, taxonomists have placed these birds in the family Emberizidae along with the New World sparrows and Old World buntings (Sulloway 1982). However, the Sibley--Ahlquist taxonomy puts Darwin's finches with the tanagers (Monroe and Sibley 1993), and at least one recent work follows that example (Burns and Skutch 2003). The American Ornithologists' Union, in its North American check - list, places the Cocos finch in the Emberizidae but with an asterisk indicating that the placement is probably wrong (AOU 1998--2006); in its tentative South American check - list, the Galápagos species are incertae sedis, of uncertain place (Remsen et al. 2007). </P> <Ul> <Li> Genus Geospiza <Ul> <Li> Española cactus finch (Geospiza conirostris) </Li> <Li> Sharp - beaked ground finch (Geospiza difficilis) <Ul> <Li> Vampire finch (Geospiza difficilis septentrionalis) </Li> </Ul> </Li> <Li> Medium ground finch (Geospiza fortis) </Li> <Li> Small ground finch (Geospiza fuliginosa) </Li> <Li> Large ground finch (Geospiza magnirostris) </Li> <Li> Common cactus finch (Geospiza scandens) </Li> </Ul> </Li> <Li> Genus Camarhynchus <Ul> <Li> Large tree finch (Camarhynchus psittacula) </Li> <Li> Medium tree finch (Camarhynchus pauper) </Li> <Li> Small tree finch (Camarhynchus parvulus) </Li> <Li> Woodpecker finch (Camarhynchus pallidus)--sometimes separated in Cactospiza </Li> <Li> Mangrove finch (Camarhynchus heliobates) </Li> </Ul> </Li> <Li> Genus Certhidea <Ul> <Li> Green warbler - finch (Certhidea olivacea) </Li> <Li> Grey warbler - finch (Certhidea fusca) </Li> </Ul> </Li> <Li> Genus Pinaroloxias <Ul> <Li> Cocos finch (Pinaroloxias inornata) </Li> </Ul> </Li> <Li> Genus Platyspiza <Ul> <Li> Vegetarian finch (Platyspiza crassirostris) </Li> </Ul> </Li> </Ul>

Where did the species on the galapagos come from