Evolutionary history of birds across southern Australia: structure, history and taxonomic implications of mitochondrial DNA diversity in an ecologically diverse suite of species

Abstract

Recent phylogeographic studies have examined the location and timing of putative Plio-Pleistocene bio-geographical barriers in moulding present-day patterns of diversity in southern Australian vertebrates. We previously investigated the divergence history of an assemblage of southern Australian birds. Here we more explicitly incorporate idiosyncratic effects of dietary ecology and habitat on the long-term demographic stability and the presence or absence of genetic structure on each of 12 species of bird. Our data suggest that the Eyrean Barrier (Flinders Ranges—Lake Eyre Basin) has been critical in shaping present-day diversity, especially that of mesic and mallee environments, and that other barriers (e.g. Murchison Barrier, Nullarbor Barrier) have played a lesser role. In contrast, nectarivory and occurrence in patchily distributed habitats are correlated with weak or no phylogeographic structure. Population expansions were most prevalent in western parts of species’ ranges. Substantial genetic divergences accompanied by moderate or no phenotypic divergence challenge traditional approaches to taxonomy in the Blue Bonnet (Northiella haematogaster), Chestnut Quail-thrush (Cinclosoma castanotum), White-eared Honeyeater (Nesoptilotis leucotis) and Scarlet Robin (Petroica boodang) and we suggest taxonomic treatments for each of these species that accommodate existing data. We elevate some taxa to species rank and note where further analyses of gene flow will be useful in clarifying remaining issues. Further phylogeographic study in the region of the Mount Lofty Ranges, Flinders Ranges, Spencer Gulf and Gulf St Vincent) of South Australia is warranted.