Population structure and evolution in subterranean mole rats ( Spalax ehrenbergi).

The overall but underestimated number of Spalax ehrenbergi in their range of 15 500 km² in Israel amounts to 1.6-2 million individuals. Populations are largely continuously distributed in their main ranges corresponding to an isolation by distance model, but become semi-isolated and isolated in their marginal peripheries. Results suggest that 1) clinal differentiation characterizes the main distributional ranges and 2) speciation may primarily originate in the peripheral small isolates where the initial fixation of spontaneous chromosomal mutations may take place by random genetic drift. Completion of speciation involves colonization of the new homozygous chromosome form into the ecological vacant niche in which it is adaptively superior to its ancestor.-from Authors