A phylogeny of the megapodes (Aves: Megapodiidae) based on nuclear and mitochondrial DNA sequences

Abstract

DNA sequences from the first intron of the nuclear gene rhodopsin (RDP1) and from the mitochondrial gene ND2 were used to construct a phylogeny of the avian family Megapodiidae. RDP1 sequences evolved about six times more slowly than ND2 and showed less homoplasy, substitution bias, and rate heterogeneity across sites. Analysis of RDP1 produced a phylogeny that was well resolved at the genus level, but RDP1 did not evolve rapidly enough for intrageneric comparisons. The ND2 phylogeny resolved intrageneric relationships and was congruent with the RDP1 phylogeny except for a single node: this node was the only aspect of tree topology sensitive to weighting in parsimony analyses. Despite differences in sequence evolution, RDP1 and ND2 contained congruent phylogenetic signal and were combined to produce a phylogeny that reflects the resolving power of both genes. This phylogeny shows an early split within the megapodes, leading to two major clades: (1) Macrocephalon and the mound-building genera Talegalla, Leipoa, Aepypodius, and Alectura, and (2) Eulipoa and Megapodius. It differs significantly from previous hypotheses based on morphology but is consistent with affiliations suggested by a recent study of parasitic chewing lice.