Multilocus genotypes from Charles Darwin's finches: biodiversity lost since the voyage of the Beagle

摘要

Genetic analysis of museum specimens offers a direct window into a past that can predate the loss ofextinct forms. We genotyped 18 Galapagos finches collected by Charles Darwin and companionsduring the voyage of the Beagle in 1835, and 22 specimens collected in 1901. Our goals were todetermine if significant genetic diversity has been lost since the Beagle voyage and to determinethe genetic source of specimens for which the collection locale was not recorded. Using 'ancient'DNA techniques, we quantified variation at 14 autosomal microsatellite loci. Assignment testsshowed several museum specimens genetically matched recently field-sampled birds from theirisland of origin. Some were misclassified or were difficult to classify. Darwin's exceptionally largeground finches (Geospiza magnirostris) from Floreana and San Cristobal were genetically distinctfrom several other currently existing populations. Sharp-beaked ground finches (Geospiza difficilis)from Floreana and Isabela were also genetically distinct. These four populations are currentlyextinct, yet they were more genetically distinct from congeners than many other species of Darwin'sfinches are from each other. We conclude that a significant amount of the finch biodiversityobserved and collected by Darwin has been lost since the voyage of the Beagle.