Genetic characteristics of hybrid populations derived by crossing Chinese and Indian pearl oysters, Pinctada fucata, based on AFLP markers

Abstract

In selective breeding, hybrid populations of pearl oysters Pinctada fucata were made by crossing Indian pearl oysters with Chinese ones. Genetic characteristics of 2 hybrid populations, Indian(♀) × Sanya(♂) and Sanya(♀) × Indian(♂) and 2 pure populations, Indian × Indian and Sanya × Sanya, were investigated using AFLP markers. A total of 230 loci were generated by 3 pairs of primer combinations. Indian-Sanya hybrid showed the highest proportion of polymorphic loci (99.6%) and the largest number of dominant, monomorphic loci (38). Gene diversity was 0.422 for total, 0.364 for average, ranging from 0.360 to 0.372. The level of gene diversity in Indian-Sanya (0.372) was significantly higher than those inthe other populations (P < 0.001). Significant and high levels of overall and pairwise genetic differentiation were observed among the 4 populations as revealed by GST and AMOVA. These results suggested that both the hybrid and pure populations were characterized by high levels of genetic diversity and genetic differentiation at the beginning of selection, implying that artificial reproduction could have more impact on genetic differentiation than on genetic diversity at the first stage of selective breeding. Yet the high level of genetic divergence among populations suggested that monitoring changes of genetic variation of selected strains is necessary and critical for rational management of brood stocks in selective breeding practice. Key words: AFLP, gene diversity, genetic differentiation, pearl oyster, hybrid population.