EVOLUTION OF LONG-DISTANCE MIGRATION IN AND HISTORICAL BIOGEOGRAPHY OF CATHARUS THRUSHES: A MOLECULAR PHYLOGENETIC APPROACH

This project was led by Diana Outlaw (former Master's student). We addressed the evolution of long-distance migration in and the historical biogeography of Catharus thrushes within a phylogenetic framework. Catharus thrushes are a Nearctic–Neotropical genus consisting of fi ve migrant and seven resident species. We reconstructed a molecular phylogeny using a combined analysis of cytochrome-b and ND2 genes. Phylogenetic reconstructions indicate the nonmonophyly of migratory Catharus species. The Neotropics are the most likely ancestral geographic area for the entire lineage, and migratory species are sister to resident taxa whose ranges are restricted to Central America, Mexico, or both. Resident behavior may be ancestral within the lineage, with migratory behavior evolving three times, although confi dence in those reconstructions is equivocal in many cases. However, uncertainty in ancestral character states presents an interesting scenario including potential drop-offs of resident species from migratory ancestors.