Genetic variation in wild and cultured populations of the pearl oyster Pinctada fucata from southern China

In order to provide information for selective breeding program in China, the genetic variation in wild and cultured Pinctada fucata populations from southern China was studied using AFLP markers. Three pairs of primers generated 182 loci among 179 individuals in populations from Beibu Bay, Daya Bay and Sanya Bay. A high level of genetic diversity, ranging from 0.367 in a wild population in Sanya Bay to 0.393 in a wild population in Beibu Bay, and high level of proportion of polymorphic loci were observed within both wild and cultured populations. Yet cultured populations in Sanya Bay and Beibu Bay had more fixed loci than the corresponding wild populations. Genetic differentiation in most pairwise comparisons of populations was significant. AMOVA indicated that genetic variation among populations was very low (1.77%) though significant, while more than 98% variation resided among individuals within population. These findings provide no evidence to show that hatchery practice of pearl oyster in China to date has significantly affected the genetic diversity of the cultured populations, and suggest that all populations are competent for selection. Yet the significant genetic differentiation among most populations implies that any translocation of individuals for genetic improvement program should be managed with caution for the preservation of genetic diversity in natural populations.