Evolutionary distinctiveness and historical decline in genetic diversity in the Seychelles Black Parrot Coracopsis nigra barklyi

摘要

Island endemic species are acutely vulnerable to extinction as a result of stochastic and human impacts. Conservation of unique island biodiversity is high priority, and an understanding of the evolutionary history of vulnerable island species is important to inform conservation management. The Seychelles Black Parrot Coracopsis nigra barklyi is an island endemic threatened with extinction. The total population of 520-900 individuals is restricted to the 38-km(2) island of Praslin, and it is one of the last few remaining endemic island parrots that survive in the Indian Ocean. We combined mitochondrial and microsatellite DNA markers with morphological data to examine the evolutionary distinctiveness of C.n.barklyi within Coracopsis, and to compare levels of genetic diversity between historical and contemporary specimens. Phylogenetic analyses revealed C.n.barklyi as sister to the remaining three C.nigra subspecies, and discriminant function analysis suggested the Seychelles Black Parrot is the smallest of the four subspecies. Higher levels of genetic diversity were observed in historical specimens, whereas only one mtDNA haplotype was observed in the contemporary specimens, suggesting that C.n.barklyi has lost genetic diversity as a consequence of substantial recent population decline. This study provides a first insight into the evolutionary, genetic and morphological processes that have shaped C.n.barklyi and provides an important perspective on this parrot's current genetic status to guide its future conservation management. Further ecological studies are essential but we suggest that C.n.barklyi should be managed as an evolutionary significant unit to conserve its unique evolutionary pathway.