Abstract
Ph.D.
A genetic study of seven fish species within the chubby and goldie barb groups of minnows was done by means of starch-gel electrophoresis. These two groups of minnows are widely distributed within the temperate rivers of southern Africa. Because of little morphological differentiation between the species within these two groups of barbs, their taxonomy has not yet been settled. Subsequently, species within these two groups of minnows could not always be identified with certainty and caused some problems for conservation bodies concerning the distribution and status of the different species. To make a contribution towards the taxonomy and conservation of these fish species, 330 specimens of goldie and chubbyhead barbs were analysed to determine the genetic variation within and between 17 populations comprising seven species.
The heterozygosity values obtained in the present study within populations is similar to the values obtained for fish in other studies (Nevo et al., 1984; Alves and Coelho, 1994). The highest heterozygosity values were observed in fish populations collected from the eastern Cape, which could possibly be an indication of a relationship between this specific habitat and genetic diversity. In contrast, relatively low heterozygosity values were observed in some populations, for example Barbus brevipinnis (Marite River) and B. gurney! (Mgeni River), which could possibly be attributed to a degraded habitat. This assumption is supported by the fact that these populations were infested with parasites, which is often an indication of stress.