中国大陆尼罗罗非鱼引进群体间遗传关系分析

为了从分子水平上评价中国大陆尼罗罗非鱼（Oreochromis niloticus）主要引进群体间遗传关系、遗传分化及基因流状况，研究利用12对多态性微卫星引物，以埃及土著群体为对照组，分析中国大陆尼罗罗非鱼9个代表性引进群体的遗传关系。结果显示:①群体间四种遗传距离D_A、D_C、D_SW和（δμ）2]同时表明，USA群体和EGY群体间的遗传距离最小D_A=0.2174，D_C=0.4140，D_SW=0.8769，（δμ）2=22.6904]；D_A和D_C表明GD群体和XJF群体间遗传距离最大（D_A=0.5851，D_C=0.6789）；D_SW和（δμ）2表明USA群体与XJF群体间遗传距离最大D_SW=4.0907，（δμ）2=138.18]。② EGY群体和GD群体间遗传分化最小（F_ST=0.0326，R_ST=0.0337），XJF群体和LY群体间遗传分化最大（F_ST=0.2098，R_ST=0.2655）。所有成对群体间均存在显著的遗传分化（P < 0.05）。③群体间系统树显示，WY群体、GD群体、EGY群体和USA群体被聚为一类，BL群体、LY群体和EW群体被聚为一类，JNM群体和GLD群体被聚为一类，XJF群体位于独立的分支；贝叶斯聚类分析将10个群体划分为2类，XJF、BL、LY、EW群体被归入第一类，WY、GD、EGY、USA、GLD和JNM群体被归入第二类。分子方差分析和主成分分析支持了系统树和贝叶斯聚类分析的结果。④根据成对F_ST值和R_ST值估算的群体间历史基因流平均值分别为2.4427和2.1983。群体间近期基因流检测结果显示，各群体中发生第一代迁移的个体数在0-7个，占样本数的0-23.3%。总体而言，我国尼罗罗非鱼引进群体间遗传分化显著，群体间存在一定程度的历史基因流和近期基因流。研究结果为开展我国尼罗罗非鱼引进群体的种质资源保护和综合利用提供了科学依据。

ANALYSIS OF GENETIC RELATIONSHIP AMONG THE INTRODUCED POPULATIONS OF NILE TILAPIA (OREOCHROMISNILOTICUS) IN CHINESE MAINLAND

To evaluate molecular genetic relationships, genetic differentiation and gene flow among the introduced po-pulations of Nile tilapia (Oreochromis niloticus) in mainland China, 12 pairs of polymorphic microsatellite primers were used to analyze genetic relationships among 10 populations of Oreochromis niloticus (one indigenous population in Egypt as the control group, nine introduced populations in mainland China as experimental group). The measures of genetic distance DA, DC, DSW, (δμ)2] showed that the genetic distance between EGY and USA was smallest DA=0.2174, DC=0.4140, DSW=0.8769, (δμ)2=22.6904]. The measures of DA and DC showed that the maximum genetic distance was between GD and XJF (DA=0.5851, DC=0.6789). The measures of DSW and (δμ)2 showed that the maxi-mum genetic distance was between USA and XJF DSW=4.0907, (δμ)2=138.18]. The measures of FST and RST showed that genetic di-fferentiation between EGY and GD was the minimum (FST=0.0326, RST=0.0337), and genetic differentia-tion between XJF and LY were the maximum (FST=0.2098, RST=0.2655). There were significant genetic differences between all pairs of po-pulations (P<0.05). Clustering relationship between populations showed that WY, GD, EGY and USA population were clustered together;BL, LY and EW population were clustered together;JNM and GLD popula-tion were clustered together. XJF population was clustered into an independent branch. Bayesian clustering analysis showed that 10 populations were clustered into two categories with XJF, BL, LY and EW in the first category popula-tion and others in the second category. The results of phylogenetic tree and Bayesian clustering analysis were suppor-ted by analysis of molecular variance and principal components analysis. The average values of historical gene flow among populations were evaluated on the basis of FST and RST, which were 2.4427 and 2.1983, respectively. Results of recent gene flow among populations showed that the first generation migrants in each population was 0—7, accounting for 0 to 23.3%of total samples. Overall, significant genetic difference was detected among introduced populations of Nile tilapia in China. And there is some historical gene flow and recent gene flow among populations. This study provided a scientific basis for protection and utilization of germplasm resources of introduced populations of Nile tilapia in China.