Genetic Diversity Among Populations of Bighead Carp (Hypophthalmichthys nobilis) Upstream and Midstream Yangtze River by Microsatellite DNA Analysis

ABSTRACT: Bighead carp (Hypophthalmichthys nobilis) has an essential role in freshwater fisheries worldwide, especially in China, yet its germplasm resources in the upstream Yangtze River have been scarcely studied. We used nine polymorphic microsatellite markers to assess genetic diversity and differentiation in seven bighead carp populations from the upper-middle Yangtze River. In five populations from the upstream and two populations from the midstream of the Yangtze River, a total of 101 alleles were detected, with the mean value of alleles per population varying from 5.3 to 8.4. Moderate genetic diversity of seven populations was detected with the values of Ho, He and PIC ranging from 0.598 to 0.683, 0.647 to 0.703 and 0.591 to 0.639, respectively. Weak population differentiations (F_st = 0.0000–0.0478) were observed, which indicated that bighead carp populations up and down the Three Gorges Dam (TGD) could be regarded as a group. Structure and clustering analysis consistently supported that the bighead carp samples examined in this study were clustered as one group, except a population from Dongting Lake (DTL), the second largest lake of China, in the midstream of the Yangtze River. This study provided evidence of moderate genetic diversity and weak differentiation among bighead carp populations from upstream and midstream regions of the Yangtze River, suggesting that the TGD has not yet had a significant influence on population genetic structure. These results are valuable for conservation genetics and sustainable utilization of bighead carp resources in the Yangtze River.