Genetic variation and an estimation of effective population size in the pearl oyster Pinctada martensii

In September 2011, two wild populations of pearl oysters were collected separately from Daya Bay, Shenzhen, and from Beibu Bay, Beihai, China. In April 2012, three cultured stocks were established by sampling breeders from the third-generation selected lines. The genetic variation within the five stocks was analyzed using eight SSR primer pairs. The effective population sizes of the five stocks were analyzed using the sibship reconstruction and multiple summary statistics methods. A total of 22-29 alleles were observed in the five stocks, with two to five alleles per locus and means ranging from 2.750 to 3.625 alleles per locus. The average expected and observed heterozygosities ranged from 0.3387 to 0.5029 and from 0.2917 to 0.4219, respectively. The effective population sizes of the five stocks ranged from 11.0 to 20.0 when estimated using sibship reconstruction and from 13.7 to 179.4 when estimated using multiple summary statistics. The effective population sizes estimated in the three cultured stocks were smaller than the number of breeders used to produce these stocks. Thus, it may be necessary to augment the number of breeders used to produce progeny stocks in selective breeding programs.