Determination of genetic diversity of South African intertidal limpets (Gastropoda: Siphonaria) with different reproductive modes using polyacrylamide gel electrophoresis of total cellular proteins

Using polyacrylamide gel electrophoresis of total soluble proteins, estimates of genetic variability were obtained from populations of seven species of southern African limpets. Among these sampled populations, greater levels of genetic variability were associated with the planktonic developing species, Siphonaria concinna, S. capensis and S. oculus with clear protein polymorphisms associated with S. concinna. The direct developing species, S. anneae, S. nigerrima, S. serrata and S. tenuicostulata were characterised by lower levels of genetic variability within a species and their mean value of genetic variability was lower than that of the planktonic developing species. All species had similar protein banding patterns and on a dendrogram produced from a similarity matrix they largely nested apart from each other and the three outgroups. The systematic relationships within Siphonaria were unclear. Six of the seven species fall into the subgenus Patellopsis but PAGE did not discriminate these from S. serrata of the subgenus Siphonaria. However, the earlier branching of the planktonic developing species with direct developing species nesting among them on the dendrogram suggests that the planktonic species may be primitive within the Patellopsis subgenus.