Los pájaros olvidadosLos granívoros extintos de la macaronesia

Resumen

Evolutionary studies of insular biotas are based on extant species despite such biotas represent reduced subsets of original faunas due to Late-Quaternary extinction events mediated by man. Therefore, the extinction of many taxa makes difficult to obtain a full understanding of the evolutionary history and ecological interactions of extant species. Morphological bill variation of common and blue chaffinches (Fringilla coelebs and F. teydea) has been studied in Macaronesia. Character displacement between both species has been argued to explain bill sizes. However, this explanation is incomplete, as similar bill patterns are recorded in common chaffinch populations from islands with and without blue chaffinches. The existence of several species of extinct greenfinches with variation in their beak sizes, suggests that the character displacement among extinct and extant finches has influenced patterns of divergence on these islands. Morphological analyses of an extinct species of Tenerife, the slender billed greenfinch Carduelis aurelioi, radiocarbon dating and the time of colonization and diversification among the extant finch species obtained from DNA sequences, provide the strongest evidence for these ancient interactions. Such a system with extinct and extant species prompts a re-thinking of the evolutionary and biogeographic history of macaronesian finches, where extinct taxa emerge as key species to understand the morphology and variation of the extant birds.