Abstract

Several stages of speciation can now be identified in some birds occurring mainly in the mulga habitat of the arid parts of Australia. Speciation in birds adapted to the stony and Triodia-sandhill deserts has occurred more commonly than previously suspected. Only sedentary birds of the mulga and desert habitats have produced differentiated isolates. The Eyrean Barrier has played an important role in the production of species adapted to arid conditions from those adapted to mesic conditions and in the speciation of inhabitants of the mulga. Some isolates of desert species may have been formed during pluvial periods in the Pleistocene.