Vocal and visual signal divergence in a Neotropical songbird
New species may arise when related animal populations diverge in their plumage and song mating signals and no longer respond to the signals of other populations. In many tropical birds, species limits are unclear because of a lack of studies on plumage, song, morphological, and genetic variation among closely-related populations. Even fewer studies investigate whether birds from different populations respond less to mating signals which differ from their own, which would prevent these populations from interbreeding. One such example is the Rufous-capped Warbler, a tropical songbird species consisting of two groups of subspecies which differ in plumage and song, but hybridize in southern Mexico. My research will resolve taxonomic relationships among Rufous-capped Warbler subspecies by measuring plumage, song, morphological, and genetic differences across the hybrid zone in Mexico, and experimentally testing the responses of three different populations of warblers to examples of plumage and song signals from both subspecies groups.