Biochemical and morphological systematics of the Southern African gastropod genera Burnupena (Buccinidae) and Oxystele (Trochidae)

Gastropods of the genus Burnupena are very common rocky-shore whelks endemic to the Southern African region. However, despite recent revisions of the genus, difficulties in identification persist, due mainly to the occurrence of phenotypic intermediates between sympatric species. Samples of Burnupena were collected from 17 sites along the coast of South Africa. Variation in shell morphology was examined using multivariate analyses. The results revealed that the degree of variation within species is very high, and that shell form and colour can be influenced by local environmental conditions. Nevertheless, most populations of the individual species clustered together. Morphological differences between species were small, although distinctions could be discerned, with not all species being confused with all other species. However, on the basis of morphology, there will always be a few individuals which will remain difficult to identify. Examination of the radulae from all of the species of Burnupena using both light and electron microscopy showed that the radula is of little or no practical value in distinguishing between species. Whilst some differences could be detected in some characters, these were not consistent, either within or between species. However, the radula is diagnostic at the generic level. The populations of Burnupena were analysed for allozyme variation at 25 loci. Variation within species was high, and in all of the species, significant population differentiation was obseNed. A significant correlation between genetic and geographic distance was found. Nei's genetic distances within species were low (means per species ranging from 0.01 to 0.05), and the populations of each species clustered together. Unlike their morphological differences, the species were mostly well differentiated genetically, with Nei's distances between species ranging from 0.1 to 1.45. Compared to the other species, B. cincta and B. lagenaria were relatively little differentiated from each other. B. catarrhacta was strongly differentiated from all of the other species. Comparisons between sympatric populations suggested complete reproductive isolation between the species.

Grantor dc:publisher.institution

Department of Biological Sciences

Year dc:date.issued

1995

Author dc:creator

• Dempster, Yvonne Laura

Advisor dc:contributor.advisor

• Branch, George M

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/11427/8496

OAI identifier oai:identifier

oai:open.uct.ac.za:11427/8496