The evolution of vocal duets and migration in New World warblers (Parulidae)

Abstract

Abstract Vocal duets occur when 2 individuals vocalize in temporal coordination. In birds, duet participation functions to cooperatively defend shared resources, localize mates, and in some species, guard the mate. Previous work indicates that duetting tends to co-evolve with a non-migratory lifestyle, probably because the absence of migration facilitates greater cooperation between mates. We examined the evolution of duetting and migration in New World warblers (Parulidae), a group that has been largely ignored by duetting research. Of the 95 species in our analysis, we found evidence of duetting in 19 (20%) species, and evidence of migration in 45 (47.4%) species. Ancestral character reconstruction indicated that the last common ancestor of the New World warblers did not duet. Duetting evolved multiple times in this group, including 2 early origins and several more recent origins. Migration was present in the last common ancestor and was lost several times. Both duetting and migration exhibit phylogenetic signal. A phylogenetically explicit correlation analysis revealed a significant negative relationship between duetting and migration, in keeping with findings from other avian taxa. This study, the first description of the evolution of duetting in a large avian family with a temperate-zone origin, supports the hypothesis that duetting co-evolves with a sedentary natural history in birds.