Effective population size and maintenance of genetic diversity in captive-bred populations of a Lake Victoria Cichlid

We used microsatellite DNA markers to investigate the maintenance of geneti c diversity within and between samples of subpopulations (spanning five cap tive-bred generations) of the haplochromine cichlid Prognathochromis perrie ri. The subpopulations are maintained as part of the Lake Victoria Cichlid species survival plan. Changes in the frequencies of 24 alleles, over four polymorphic loci, were used to estimate effective population size (N-e). Po int estimates of N-e ranged frp, 2.5 to 7.7 individuals and were significan tly smaller than the actual census size (N-obs) for all subpopulations (32- 243 individuals per generation), with the corresponding conservative N-e/N- obs ratios ranging from 0.01 to 0.12. Approximately 19% of the initial alle les were lost within the first four generations of captive breeding. Betwee n-generation comparisons of expected heterozygosity showed significant loss es ranging from 6% to 12% per generation. Seven private alleles were observ ed in the last sampled generation of four subpopulations, and analysis of p opulation structure by F-ST indicated that approximately 33% of the total g enetic diversity is maintained between the subpopulations from different in stitutions. To reduce the loss of genetic variation, we recommend that offs pring production be equalized by periodically removing dominant males, whic h will encourage reproduction by additional males. Consideration should als o be given to encouraging more institutions to maintain populations, becaus e a significant fraction of the genetic variation exists as among-populatio n differences resulting from random differentiation among subpopulations.