Loss of genetic variation at microsatellite loci in hatchery strains of the Pacific abalone ( Haliotis discus hannai)

Abstract

In order to assess the utility of microsatellite DNA markers for detecting changes of genetic diversity in hatchery strains and for estimating their genetic relationships, we used six microsatellite markers to estimate the level of genetic diversity within three hatchery strains and two wild populations of Pacific abalone, and compared the degree of genetic differentiation between them. High polymorphism at the microsatellite loci was found within both hatchery and wild abalone populations. Compared to wild populations, all the hatchery strains showed less genetic variation as revealed in lower number of alleles and lower expected heterozygosity, indicating that bottleneck effects occurred when each strain was founded. Significant differentiation was found between the hatchery strains, and between the hatchery strains and wild populations ( F st range: 0.059–0.427; R st range: 0.056–0.351), and no obvious difference was detected between the wild populations ( F st=0.004; R st=0.007). According to the neighbor-joining tree topology constructed on the basis of genetic distances among individuals, almost all individuals from each hatchery strain were closely clustered, demonstrating the feasibility of microsatellite analysis for discrimination between hatchery strains. The results obtained in this study indicate that it is necessary to genetically characterize the abalone strains that are being released every year in order to monitor the effect on the genetic diversity of wild populations.