Population fragmentation in the southern rock agama, Agama atra: more evidence for vicariance in Southern Africa.

Mitochondrial DNA sequence data derived from two genes were used to infer phylogeographical relationships between 13 Agama atra populations. Three distinct geographical assemblages were found among the lizard populations. The first occurs in southern Namibia, the second is restricted to the western dry arid regions of South Africa, whereas the third is distributed throughout the more mesic southern and eastern parts of the subcontinent. Geographically structured differences among populations within Agama clades are probably the result of dispersal and historic isolations among populations. At the broader scale, there were marked congruences between the Agama genetic discontinuities and those described previously in other rock-dwelling vertebrates such as Pronolagus rupestris and Pachydactylus rugosus. This suggests vicariance, probably as a response to natural climatic changes during the past three million years.