三峡库区5个鲢群体遗传变异的微卫星分析

THE MICROSATELLITE ANALYSIS OF GENETIC DIVERSITY OF FIVE SILVER CARP POPULATIONS IN THE THREE GORGES RESERVOIR OF THE YANGTZE RIVER

研究利用10个高度多态的微卫星标记对三峡水库秭归、巫山、云阳、忠县、木洞等5个库区鲢(Hypophthalmichthys molitrix)的野生群体进行了遗传多样性分析。检测到161个等位基因,群体共有等位基因84个,每个微卫星位点的等位基因数7—29不等。平均观测杂合度Ho为0.784—0.846,平均期望杂合度He为0.828—0.847,平均多态信息含量PIC为0.797—0.817。Fst值为–0.001—0.009,表明5个鲢群体间没有遗传分化。Hardy-Weinberg平衡检验表明巫山、云阳、木洞群体在一些位点上偏离遗传平衡。Bottleneck分析显示长江三峡库区江段的鲢群体可能在历史上经历了遗传瓶颈。5个群体间的遗传相似系数为0.891—0.950,遗传距离为0.050—0.115,根据Nei’s遗传距离所绘制的聚类图,表明鲢群体间的遗传距离与其地理距离基本一致。贝叶斯分析结果也证实三峡库区5个鲢群体可视为一个类群。尽管没有检测到遗传分化,数据清晰地表明三峡库区的鲢群体仍有很高的遗传多样性,研究结果为三峡地区和长江上游的鲢种质资源保护和种群评估提供了参考。

In this study we employed ten microsatellite markers to analyze the genetic diversity of five silver carp populations including Zigui, Wushan, Yunyang, Zhongxian and Mudong in the Three Gorges Reservoir of the Yangtze River. A total of 161 different alleles were detected, and 84 of them were common in all 5 populations. The number of alleles per locus ranged from 7 to 29. In the five populations, the average values of observed and expected heterozygosity ranged from 0.784 to 0.846 and 0.828 to 0.847 respectively, and the mean PIC was 0.797 to 0.817. The Fst values were between -0.001 and 0.009, which indicated that the genetic differentiation was not significant. Chi-square test was used to analyze the genotypes based on the Hardy-Weinberg equilibrium, and the P value indicated that some loci in three populations deviated from the HWE. The bottleneck analysis revealed that the silver carp populations from the Three Gorges Reservoir of the Yangtze River might have undergone a recent genetic bottleneck. The genetic similarity coefficient of the five populations was between 0.891 and 0.950, and the genetic distance of the populations was between 0.050 and 0.115. We also constructed the phylogenetic tree of the five silver carp populations based on Nei＇s standard genetic distance, and the results showed that genetic distances between the populations were consistent with their geographical distances. The Bayesian analysis also suggested that the silver carp samples from the 5 locations of the Three Gorges Reservoir could be characterized as a single population. Although we did not observe the genetic differentiation, silver carp populations in the Three Gorges Reservoir displayed high genetic diversity. Our study provided valuable information on the genetic resources of silver carps in the Three Gorges Reservoir and in the upstream of the Yangtze River, which should help develop appropriate policies on the conservation and utilization of silver carps.