Phylogenetics of Darwin's finches: Paraphyly in the tree-finches, and two divergent lineages in the warbler finch

Abstract

The Galapagos Darwin's finches (Geospizinae) have been classified as three major groups based on morphology and behavior: ground-finches, tree-finches, and the Warbler Finch (Certhidea olivacea). Little is known about the evolutionary relationships within and among these groups, which is partly due to the lack of a phylogeny based on molecular sequence data. We used mitochondrial sequence data to reconstruct a phylogeny of Darwin's finches. These data show that within the tree-finches, only one genus is conclusively monophyletic, and another is conclusively paraphyletic. It may be appropriate to uphold the classification of the tree-finches into two genera. The Warbler Finch complex is paraphyletic, as revealed by two divergent genetic lineages contained within this species. Stochastic lineage sorting within relatively recently diverged species and interspecific and intergeneric hybridization are the two most likely explanations for the sharing of haplotypes among taxa.