Microsatellite analysis of genetic diversity in wild and cultivated Portunus trituberculatus in Bohai Bay.

Abstract

Previous studies have revealed a reduction in the genetic diversity of P. trituberculatus in Bohai Sea. However, because swimming crabs have been released into this area for some time, it is unclear whether the release of cultured populations from the national breeding farms of swimming crabs in Bohai Bay have affected the population genetics of wild populations of P. trituberculatus. In this study, the genetic diversity and population structure of 120 P. trituberculatus specimens in Bohai Bay were investigated using six microsatellite loci, including one wild population and one cultivated population. A total of 132 alleles were identified for all loci. The mean expected (He) and observed heterozygosity (Ho) were 0.8185 and 0.7759, respectively, thus indicating high levels of genetic diversity for these two populations. Molecular variance analysis (AMOVA) (FST = 0.0180), genetic distance (D = 0.1168) and similarity (S = 0.8898) indicated that these two populations could not be distinguished genetically. Structural analysis, phylogenetic tree construction, and principal component analysis, showed no significant distinction between the wild and cultivated populations. Finally, we investigated genetic exchange between the two populations by analyzing migration rate (M) and gene flow (Nm), thus demonstrating significant flow of genetic information. These findings contribute information for further breeding schemes for P. trituberculatus, evaluation of its genetic potential and programs for the protection of wild resources.