Evidence for the Species Status of the Bahama Yellow-Throated Warbler (Dendroica “Dominica” Flavescens)

摘要

The Bahama subspecies of the Yellow-throated Warbler (Dendroica dominica flavescens) was originally described as a species. However, it was later reclassified as a subspecies, in part because the trinomial was considered useful for demonstrating relationships. Although flavescens has been widely reported as diagnostic in plumage and distinctive in ecology, it has remained a subspecies of D. dominica, perhaps because of the notion that its song is similar to that of continental dominica. We investigated the taxonomic status of flavescens by examining morphological, song, and genetic data. We found statistically significant differences between flavescens and continental dominica in wing chord and in bill, tarsus, and tail lengths. Discriminant function analysis correctly predicted 100% of flavescens individuals using morphological characters. Contrary to earlier accounts, we also found the ascending song of flavescens to be diagnosable from the descending song of continental dominica. Mitochondrial control-region sequence data revealed fixed differences and a 1.0% divergence between flavescens and continental dominica. Phylogenetic analysis indicated that flavescens samples form a monophyletic group and that continental dominica is paraphyletic with respect to flavescens. This is consistent with a scenario of peripatric speciation: complete lineage sorting in the flavescens population but incomplete lineage sorting in the much larger continental dominica population. We conclude that flavescens satisfies the requirements of both the biological and phylogenetic species concepts, and we therefore recommend that flavescens be reclassified as a separate species, the Bahama Warbler (Dendroica flavescens).