Evolution and biogeography of the Australian grasswrens, Amytornis (Aves : Maluridae): biochemical perspectives

Abstract

Allozymes at 35 presumptive loci were screened across 43 specimens representing seven of the eight currently recognised species of Australian grasswrens (Maluridae). The results identified an early divergence between the grey grasswren, Amytornis barbatus, and the remaining species examined. The patterns of genetic divergences between species of Amytornis examined suggest that the taxa occurring in central and western Australia diversified 100 000 years ago while those forms restricted to the rocky outcrop regions around the periphery of the continent diverged much earlier (some 2-3 million years ago). The Eyrean grasswren, A. goyderi, was part of an assemblage that included the thick-billed grasswren, A. textilis (represented in this study by the forms myall and modestus), the dusky grasswren, A. purnelli, and possibly the black grasswren, A. housei. The white-throated grasswren, A. woodwardi, appeared to be related to the striated grasswren, A. striatus (represented in this study by the forms striatus and merrotsyi) although this association was not consistent across all tree-building methods. The high genetic distance recorded between the two forms of A. striatus examined (0.184) was at the higher end of the range for interspecific comparisons within the genus (0.021-0.316). The two forms were not identified as sister taxa in any of the distance-based and discrete character-state trees. It is recommended that A. merrotsyi be recognised as a species separate from A. striatus, a conclusion supported also by morphological characters.