Low genetic diversity and genetic differentiation among domesticated stocks of the small abalone Haliotis diversicolor in China

AFLP markers were used to investigate levels of genetic diversity within cultured populations of the small abalone Haliotis diversicolor in China and to compare them with a wild population. A total of 234 fragments, with a size range of 150-500 bp, were identified from 152 individuals by five AFLP primer combinations. High proportion of polymorphic loci (77.65%) and heterozygosity (0.2124) were found within the natural population, while low proportion of polymorphic loci (24.51 to 64.31%) and heterozygosity (0.0677 to 0.1665) were detected within the six cultured populations. The results show a significantly reduced genetic diversity in the hatchery stocks when compared with the wild population. AMOVA analysis, pairwise comparison of φST values, and cluster analysis showed that both the wild population (DX) and the stock (TW) were significantly different from the other five domestic cultured populations. For the five hatchery stocks sampled from mainland China coast, however, genetic differences were not significant, except between SZ and ZJ, SZ and HN stocks. The genetic status detected in this study hints that mass mortality of H. diversicolor in recent years might have association with the reduction in genetic diversity. The results also indicate that all cultured populations, excluding TW and ZJ stocks, may not be suitable as source populations for selective breeding programs; some natural populations and foreign stocks introduced from outside China should be considered.