Mitochondrial DNA differentiation in the critically endangered Berg River redfin (Pseudobarbus burgi)

The Berg River redfin (Pseudobarbus burgi) is a critically endangered endem ic cyprinid from South Africa. We investigated mitochondrial DNA control re gion variation among specimens representative of five populations drawn fro m two adjacent river systems. Phylogenetic analyses, a minimum spanning net work, and an analysis of molecular variance underscore the pronounced genet ic separation of redfins originating from the geographically closely allied Verlorevlei and Berg Rivers, two populations that may have remained isolat ed since the Pleistocene. Despite a lack of geographic structuring within t he Berg River, historic female gene flow among the upper and middle/lower p arts of the river appears to be limited and the contemporary populations ar e probably isolated due to deterioration of the mainstream of the river. Ou r results suggest that the Berg and Verlorevlei populations should be manag ed as distinct conservation units. We encourage the use of sanctuaries, par ticularly by private landowners within both river systems, as this approach may contribute effectively to preserving genetic diversity within the spec ies.