Anna Kearns, Lauren White, Jeremy Austin, Kevin Omland. Distinctiveness of Pacific Robin subspecies in Vanuatu revealed from disparate patterns of sexual dichromatism, plumage colour, morphometrics and ancient DNA. Emu - Austral Ornithology, Just accepted article.
The Pacific Robin (Petroica multicolor) is a polytypic species with 14 subspecies recognised across the tropical south-west Pacific. Like most of this regionâs avifauna, the Pacific Robin has received little taxonomic attention since the works of those like Ernst Mayr in the 1930-1950s. Here, we used mtDNA, spectrophotometry of plumage colour and morphometric measurements to explore patterns of sexual dichromatism, and phenotypic and genetic variation of Pacific Robins in the Vanuatu archipelago. We showed for the first time that subspecies in Vanuatu display three types of sexual dichromatismâ€” typical marked sexual dichromatism, and reduced sexual dichromatism where both sexes have either elaborate masculinised plumage or drab feminised plumage. Different types of sexual dichromatism were not correlated with phylogenetic relationships. We also find that distinctive mtDNA, bill length and throat plumage colour support the naming of a new subspecies for the population on Tanna Island, P. m. tannensis subsp. nov.
, which has long been treated as consubspecific with that on nearby Aneityum Island. Our study highlights the importance of revisiting the taxonomy and evolutionary history of other Pacific avifauna with molecular data and quantitative tests of phenotypic differentiation between island forms.