Discordance between morphology and genetic structure among three plumage forms of the Australian Magpie

Abstract

The present study examined the extent of gene flow and population genetic structure among the highly sexually dimorphic form of the Australian Magpie (Gymnorhina tibicen dorsalis) which is restricted to the southwestern corner of the continent, and neighbouring plumage forms in north-western and eastern Australia. A phylogenetic break in the mtDNA haplotype phylogeny was evident between all western and all eastern plumage forms. The inference is that dispersal between eastern and western Australia is limited by large areas of unfavourable habitat, which isolate the two plumage forms. In contrast, there is no evidence of historic genetic structure among plumage forms in Western Australia and so their distributions are not explained by historical isolation and independent evolution. The results are consistent with a primary origin hypothesis for the plumage differences between the varied and western black-back forms of the Australian magpie.