基于线粒体NADH脱氢酶亚基2标记的东南太平洋不同表型间茎柔鱼群体遗传学分析

Population genetic structures of Dosidicus gigas in Southeast Pacific Ocean based on mitochondrial NADH dehydrogenase subunit 2 gene

为了解东南太平洋茎柔鱼(Dosidicus gigas)大、中、小3种表型群体间的遗传分化和结构,利用线粒体NADH脱氢酶亚基2(ND2)基因,对东南太平洋大、中、小3种表型群,共90尾性成熟茎柔鱼样本进行群体遗传学研究。ND2基因序列测序结果显示3个表型群总的单倍型多样性指数(H_(d))为0.818,核苷酸多样性指数(P_(i))为0.00240,表现出较高的单倍型多样性和较低的核苷酸多样性。来源于群体内的变异达到了100.45%,两两群体间的遗传分化系数(F_(st))均小于0.05(P>0.05),且基因流(N_(m))远大于1,说明3种表型的茎柔鱼未出现显著的遗传分化。中性检验呈极显著负值(F_(st)=-8.61773,P<0.01),核苷酸错配分布曲线均出现明显单峰,推测东南太平洋茎柔鱼在历史上可能经历过快速的群体扩张事件。该研究结果表明分布于东南太平洋不同海域茎柔鱼大、中、小3个表型群之间因生殖行为可能存在广泛的基因交流,应属于同一个种群,在渔业管理上应予以充分考虑。

To understand the genetic differentiation and structure among the large,medium and small phenotypic groups of Dosidicus gigas in the Southeast Pacific Ocean,we studied a total of 90 samples of matured D.gigas from different phenotypic groups for population genetics by using the mitochondrial NADH dehydrogenase subunit 2(ND2)gene.The average haplotype diversities(H_(d))and nucleotide diversities(P_(i))of the three groups of D.gigas were 0.818 and 0.00240,respectively,showing a high haplotype diversity index but a low nucleotide diversity index.The genetic variation observed within populations reached100.45%.The value of genetic differentiation index(F_(st))was less than 0.05(P>0.05),but the gene flow(N_(m))was far more than 1,indicating no significant genetic divergence among the three phenotypes of D.gigas.The neutrality test was highly significantly negative(F_(st)=-8.61773,P<0.01)and the nucleotide mismatch distribution curves all showed significant single peaks,suggesting that D.gigas in the Southeast Pacific Ocean might have historically experienced rapid population expansion events.In conclusion,there may be extensive genetic exchange between different phenotypic groups of D.gigas in Southeast Pacific Ocean due to their reproductive behavior and that they should belong to the same stock,which must be fully considered in fisheries management.