On species pairs among southern African amphibians

Abstract

At least five species pairs of southern African anurans show phenetic evidence of widespread sympatric hybridization. One member of each pair can be designated ‘nontropical’ (in a thermal, not cartographic sense), the other ‘tropical’. Climatic fluctuations in the late Quaternary are seen to be involved in the process of speciation. Present altitudinal and latitudinal zonation of temperature seem involved in the maintenance of present range differences between members of pairs. A relatively complex situation is described in Breviceps, where, in the region of Zambia, the separation of one pair appears to be maintained by the intrusion of another pair.