Analyses of Genetic Diversity and Parentage Within a South African Hatchery of the Abalone Haliotis Midae Linnaeus Using Microsatellite Markers (Report‪)‬

ABSTRACT Six microsatellite DNA markers were used to investigate the levels of genetic diversity and to determine parentage in a South African hatchery of the abalone Haliotis midae. Samples examined from the farm consisted of three broodstock groups and their respective F1 offspring. Additional wild samples were collected at sites on the East and West coast of South Africa from where the broodstock samples were originally collected. All samples showed significant departures from HWE over all loci. Observed heterozygosity, Ho, for the broodstock samples ranged from 0.5366-0.6121 and from 0.5105-0.6179 for the F1's. The overall number of observed alleles, [n.sub.a], for the broodstock samples ranged from 11-12 and for the F1's from 6-10, the allelic richness, A, for the broodstocks ranged from 9.9-10.1 and for the F1's from 5.3-8.9. No loss of heterozygosity was observed between wild and broodstock samples or between broodstock and F1 samples. Only one of the three cohorts showed a significant loss in average number of alleles where a 63% reduction was observed between the F1 and its corresponding broodstock. Only three out of six markers were suitable for parental assignment, with a combined exclusion probability of 88% for the first and 97% for the second parent. Eight percent of the F1 individuals remained unassigned. The results obtained warn of the cumulative effect of differential parental contributions and possible selection pressures negatively influencing the genetic diversity within farm populations. The data would assist in designing management strategies, selection programs, as well as reseeding programs. KEY WORDS: differential parental contribution, genetic diversity, Haliotis midae, microsatellites, parentage