Genetic analysis of the Australian whipbirds and wedgebills illuminates the evolution of their plumage and vocal diversity

Abstract

Morphological and vocal diversity among closely related species reflects a combination of shared ancestry and recent species-specific adaptations. A small group of Australo-Papuan passerines in the core Corvoidea, the whipbirds and wedgebills (Psophodes, Androphobus), provide an opportunity to explore this. Vocally, the Western Whipbird (Psophodes nigrogularis sensu lato) is very similar to the two species of wedgebills, whereas the sibilant whipcrack-like song of male Eastern Whipbirds is distinctive among the group. Using phylogenetic analysis of mitochondrial DNA we show that Australian whipbirds are not sister taxa but that the Eastern Whipbird is sister to the wedgebills and that the Western Whipbird is sister to the other three members of the group. Wedgebills are nested within the whipbird clade, supporting their current inclusion in Psophodes. The topology and reconstruction of ancestral states suggests the similarity in vocalisation among wedgebills and the Western Whipbird is a result of shared ancestral character states, whereas the whipcrack-like song of the Eastern Whipbirds is autapomorphic.