Plumage diversity in the Adelaide Rosella: a case for taxonomic revision

In a quantitative and statistical analysis of plumages in the Adelaide Rosella we show variation throughout its distribution and latitudinal change from chiefly red in the south through orange in the centre to yellow in the north, consistent with Gloger’s ecophenotypic rule. We find that the change is clinal through southern and central populations, whereas a northern population in the South Flinders Ranges is essentially allopatric and shows no recognisable latitudinal change. Sexual dichromatism is present in northern populations. Our results highlight the potential influence, on plumages at endpoints in the cline, of the Kangaroo Island
Rosella in the south and Flinders Rosella in the north, suggesting past and/or continuing gene flow. We propose a taxonomic revision for the Adelaide Rosella that reflects our findings.