Integrating phylogenetic and population genetic analyses of multiple loci to test species divergence hypotheses in Passerina buntings

Phylogenetic and population genetic analyses of DNA sequence data from 10 nuclear loci were used to test species divergence hypotheses within Passerina buntings, with special focus on a strongly supported, but controversial, sister relationship between Passerina amoena and P. caerulea inferred from a previous mitochondrial study. Here, a maximum-likelihood analysis of a concatenated 10-locus data set, as well as minimize-deep-coalescences and maximum-likelihood analyses of the locus-specific gene trees, recovered the traditional sister relationship between P. amoena and P. cyanea. In addition, a more recent divergence time estimate between P. amoena and P. cyanea than between P. amoena and P. caerulea provided evidence for the traditional sister relationship. These results provide a compelling example of how lineage sorting stochasticity can lead to incongruence between gene trees and species trees, and illustrate how phylogenetic and population genetic analyses can be integrated to investigate evolutionary relationships between recently diverged taxa.