中国沿海6个花鲈群体的遗传多样性分析

利用8对微卫星或简单重复序列microsatellite or simple sequence repeats(SSR)]标记对辽宁东港(DG)、绥中(SZ),河北秦皇岛(QHD),山东青岛(QD),浙江舟山(ZS)以及广东珠海(ZH)海域的6个花鲈(Lateolabrax maculatus)群体进行遗传多样性分析。结果表明,共检测到等位基因90个,每个位点的等位基因数(NA)为3~20;有效等位基因数(Ae)为1.7~11.4;观测杂合度(Ho)为0.355~0.971;期望杂合度(He)为0.398~0.912;多态信息含量(PIC)为0.365~0.906;6个群体的遗传多样性处于中等水平且群体间差异不显著(P0.05),其中舟山群体的遗传多样性最高(NA=11;He=0.762;PIC=0.734),绥中群体的遗传多样性最低(NA=9.8;He=0.721;PIC=0.692);哈代?温伯格平衡检验显示,除秦皇岛群体外,标记Lama18、Lama21和Lama29在其他5个群体中偏离HWE(P0.01)。位点Lama18与Lama42间存在极显著性的连锁不平衡(P0.01);分子方差(AMOVA)分析结果显示群体间、群体内个体间以及所有个体间的方差均达显著性水平(P0.01);群体间配对Fst(pair-wise Fst)和遗传距离分析结果显示,舟山群体与其他5个群体遗传分化最远,遗传距离最大,而北方的绥中、东港、青岛以及秦皇岛4个群体间分化不显著;聚类分析显示,珠海与秦皇岛群体先聚合,再与舟山群体聚为一支。绥中、东港、青岛群体聚为一支;遗传组分分析结果显示,6个花鲈群体中共包含3个主要遗传组分,其中舟山群体遗传混杂少,遗传信息保留完整,而绥中、东港和青岛3个群体遗传组分类似,遗传混杂严重。另外,秦皇岛与珠海群体约40%的遗传组分相同;研究结果表明,中国沿海的花鲈群体中除舟山群体外,绥中、东港、青岛、秦皇岛和珠海5个群体的遗传多样性已受到现有养殖模式与养殖逃逸的影响。

Genetic variability in six Lateolabrax maculatus populations inhabiting the Chinese coast

Lateolabrax maculates is a rapidly maturing fish and an important aquaculture species in China. A comprehensive analysis of the genetic structure of a germplasm resource is an essential prerequisite for their ef-fective protection and utilization. The genetic diversity and structure of six L. maculatus populations—Donggang (DG), Qingdao (QD), Qinhuangdao (QHD), Suizhong (SZ), Zhuhai (ZH), and Zhoushan (ZS), inhabiting the Chinese coast were determined using eight microsatellite DNA markers. A medium level of genetic diversity was detected among the six populations but no significant differences were observed. Population SZ had the least genetic di-versity, whereas ZS had the most. Most populations, except QHD, had a significant loss of heterozygosity (P<0.01), which was also revealed by the global Hardy–Weinberg equilibrium (P<0.01). Linkage disequilibrium was extremely significant (P<0.01) between the Lama 18 and Lama 42 markers. The analysis of molecular variance results detected a significant difference in variance between populations, between individuals, and between indi-viduals within populations (P<0.01); the pair-wiseFst between groups and genetic distance results showed that maximum genetic differentiation and genetic distance occurred between ZS and the other five populations. No significant genetic differentiation was detected among the SZ, DG, QHD, and QD populations. A cluster analysis showed that ZS, ZH, and QHD were clustered with SZ, DG, and QD. Three genetic compositions were observed in the six populations. The genetic information in ZS was intact and was not mixed. The other five populations had a similar genetic composition and were significantly mixed genetically. Approximately 40% genetic similarity was detected between QHD and ZH. These results indicate that genetic differentiation has occurred between the ZS population and the other five populations analyzed. The genetic diversity among the five populations (DG, QD, QHD, SZ, and ZH) ofL. maculatus inhabiting the Chinese coast has decreased and has become more homogene-ous due to interactions with escapees from local aquaculture operations.