Molecular and morphological approaches to taxonomy and historical biogeography of Yellow-tailed Black Cockatoos ( Zanda funerea )

Prompted by a recent taxonomic proposal to divide the Yellow-tailed Black Cockatoo Zanda funerea into three species essentially based largely on morphometrics, we examined the species’ genetic diversity through single nucleotide polymorphism data from 64 individuals across its range. We also present independent morphometric and plumage data from 237 specimens. Patterns of genetic diversity are entirely consistent with one species and we reject the three species hypothesis. We confirm the well-established larger size of central east coast Australian populations relative to all others. An apparent latitudinal cline in genetic data among these eastern mainland populations extends as far west as to around Port Phillip Bay in Victoria and has a disjunction at the Hunter River. Genetic and morphological data agree that these large-bodied mainland populations are distinct with respect to those from Tasmania and South Australia. The latter includes that state’s far south-east close to its border with Victoria. Another possible disjunction at the Bassian Volcanic Barrier in western Victoria warrants testing. Magnitudes of genetic disjunctions were low, and population differentiation measured by FST was non-significant. We reject a null hypothesis of no geographic structure but acknowledge that discernible structure is weak and that it is difficult to separate it from isolation-by-distance. Nonetheless, genetic data show little correlation with any recently or currently recognised subspecies within Z. funerea beyond, possibly, differentiating large-bodied eastern mainland populations from all others.