Albumin and Australian frogs: molecular data a challenge to speciation model.

Vertebrate speciation in the southwest of Australia has long been viewed as resulting from multiple invasions of eastern source stocks during the Pleistocene. Microcomplement fixation studies of serum albumin evolution in frogs of the genus Heleioporus provide the first hard data on age and phylogenetic relationships among species in this genus and lead to rejection of the multiple invasion model in favor of speciation occurring in Western Australia. The albumin molecular clock was used to estimate that the species divergences in this genus occurred between 4 million to 12 million years ago in the late Tertiary (Pliocene-Miocene), rather than in the Quaternary (the last 2 million years).