Rise (and demise?) of subspecies in the Galah (Eolophus roseicapilla), a widespread and abundant Australian cockatoo

Abstract

The Galah (Eolophus roseicapilla) is a widespread Australian bird. Its geographical variation and subspecies remain poorly understood. We sampled 192 specimens from across the entire range of the species to assess its phylogeographical structure using the mitochondrially encoded NADH dehydrogenase 2 (MT-ND2) gene. A subset of specimens was examined for nuclear DNA diversity using the Amplified Fragment Length Polymorphism (AFLP) method. Weakly defined structure was evident in the mitochondrial DNA (mtDNA) data, which suggested three geographically defined haplogroups that broadly coincide with the three conventionally recognised subspecies: E. r. roseicapilla—western haplogroup; E. r. albiceps—eastern haplogroup; and E. r. kuhli—northern haplogroup. The three haplogroups all overlap and intersect broadly across the centre of the Australian continent. Geographical expansions of each haplogroup appear to have occurred before and after the Last Glacial Maximum (~20 000 years ago), the species itself probably having undergone an earlier expansion at c. 60 000 years ago. The preliminary nuclear AFLP data suggest very little structure though they likely track more recent processes of gene flow and population admixture. Expansion of the species since European settlement represents another, later expansion uncoupled from what is tracked in the mtDNA data. Future quantitative analyses of phenotypic variation will enhance the precision of how geographical variation in all datasets in this species should be interpreted.