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

Allozymes at 35 presumptive loci were screened across 43 specimens represen ting seven of the eight currently recognised species of Australian grasswre ns (Maluridae). The results identified an early divergence between the grey grasswren, Amytornis balbatus, and the remaining species examined. The pat terns of generic divergences between species of Amytornis examined suggest that the taxa occurring in central and western Australia diversified 100 00 0 years ago while those forms restricted to the rocky outcrop regions aroun d the periphery of the continent diverged much earlier (some 2-3 million ye ars 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 po ssibly the black grasswren, A. housei. The white-throated grasswren, A. woo dwardi, appeared to be related to the striated grasswren, A. striatus (repr esented in this study by the forms striatus and merrotsyi) although this as sociation was not consistent across all tree-building methods. The high gen etic distance recorded between the two forms of A. striatus examined (0.184 ) was at the higher end of the range for interspecific comparisons within t he 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 recomm ended that A. merrotsyi be recognised as a species separate from A. striatu s, a conclusion supported also by morphological characters.