Taxonomy and variation of the chestnut-shouldered wrens of Western Australia.

Abstract

In their zone of geographical overlap in Western Australia, Malurus pulcherrimus and M. lambertl mastersi behave as distinct species by not interbreeding despite occupying seemingly identical habitats. Where M. elegans and M. pulcherrimus come into close geographical contact, competition is avoided by the ecological unsuitability of each other's habitat. Contact between M. dulcis rogersi and M. lambertl mastersi in the south Kimberleys is unknown. No geographical variation apparently occurs in M. elegans and M. pulcherrimus in the south-west, while M. lamberti mastersi tends to be smaller in inland and northern areas, the trend being correlated with the temperature gradient. The Gloger and Bergmann effects occur at the interspecific level in the M. lamberti superspecies in south-western Australia. On Bernier Island the distinctive subspecies M. lamberti bernleri has taken at the most 8,000 years to attain its present status. On the basis of morphological criteria, M. dulcis is considered worthy of specific rank, and is divisible into two subspecies – rogersi in the Kimberleys and dulcis in the Northern Territory.