________________________________________________________________________________ AbstractThis paper details genetic characterization and trends from a microsatellite-based study of genetic diversity on southern African pig populations. A total of 351 pigs from three commercial breeds and three indigenous populations were genotyped at 39 loci. Differences among the levels of genetic diversity in populations correlated well with known population histories. In commercial breeds, heterozygosity was higher in the well established SA Landrace and Large White breeds (0.580 and 0.636) compared to the Duroc breed, established more recently (0.531). In indigenous populations, the highest heterozygosity levels were found in the Mozambican and South African populations (0.692 and 0.634) with a lower value of 0.531 in a smaller Namibian population. A hierarchical division of total genetic diversity revealed a high betweenpopulation component of 17.9%. F ST -and R ST -based analysis confirmed high levels of differentiation, with pair-wise comparisons between breeds indicating significant differentiation in 20 out of 21 comparisons.Results from an assignment test confirmed results from F ST and R ST and suggested a true genetic structure with significant differentiation between most populations sampled, but with little differentiation among the commercial SA Landrace and Large White breeds. The results are discussed with reference to known historical information on commercial and indigenous pig populations. This paper also presents new data on the optimization of microsatellite markers for application in Sus scrofa domestica.

The Afrikaner is an indigenous South African breed of "Sanga" type beef cattle along with breeds such as the Drakensberger and Nguni. Six composite breeds have been developed from crosses with the Afrikaner. Additionally, Afrikaner has been the base from which exotic breeds were established in South Africa through backcrossing. The study examined genetic diversity of Afrikaner cattle by genotyping 1257 animals from 27 herds in different geographic areas of South Africa and Namibia using 11 microsatellite markers. Multiple-locus assignment, performed using the Bayesian clustering algorithm of STRUCTURE, revealed three underlying genotypic groups. These groups were not geographically localized. Across herds and markers, the proportion of unbiased heterozygosity ranged from 0.49 to 0.72 averaging 0.57; mean number of alleles per locus ranged from 3.18 to 7.09, averaging 4.81; and allelic richness ranged from 2.35 to 3.38, averaging 2.67. It is concluded that a low inbreeding level of 2.7% and a moderate to high degree of variation still persists within the Afrikaner cattle breed, despite the recent decline in numbers of animals.

The Afrikaner is one of three indigenous cattle breeds found in South Africa. Afrikaner cattle were originally extensively used for crossbreeding purposes and breed development. The objective of this study was to determine the genetic diversity of selected stud and commercial herds from the whole South African Afrikaner population, as well as to determine the genetic structure among these herds. Assignment methods (based on STRUCTURE software) revealed a real structure consisting of four genetic populations (K = 4). Estimates of genetic diversity did not support the hypothesis of significant loss of genetic diversity in any individual Afrikaner herd. Heterozygosity estimates ranged from 0.456 - 0.737 within individual populations, with an overall heterozygosity estimate of 0.568 for the Afrikaner breed. The average number of alleles per locus was regarded as being 2.67 - 7.78, with an average of 5.18 alleles per locus. It could be concluded that a moderate to high degree of variation is still present within the Afrikaner cattle breed, despite the recent decline in numbers of this indigenous breed.Keywords: Bos taurus africanus, heterozygosity, inbreeding, microsatellite markers