基于线粒体COI基因分析钩手水母的群体遗传结构

钩手水母(Gonionemus vertens)为大西洋和太平洋广布种, 是我国习见的有毒水母种类之一。本文对采自黄渤海海域4个地理群体的104个钩手水母线粒体COI基因序列进行扩增, 并结合GenBank上其他182个钩手水母同源序列进行序列变异分析。在286个基因序列中共检测出52个多态位点, 定义了14种单倍型。总群体的单倍型多样性和核苷酸多样性分别为0.743 ± 0.012和1.046% ± 0.097%, 与其他几种大型水母相比, 钩手水母总群体的遗传多样性处于较高水平。AMOVA结果显示, 60.17%的分子变异源于群组间, 13.37%的分子变异源于群体内, 26.46%的分子变异源于组内群体间, 群组间、群体内和组内群体间的遗传分化均极显著。F_st值统计检验表明, 中国厦门群体与乐亭、东营、烟台、大连群体间存在显著的遗传分化, 大连与东营、烟台群体间也存在显著的遗传分化。系统分析结果显示, 钩手水母群体间存在2个明显的单倍型谱系分支。不同的钩手水母地理群体间具有复杂的遗传模式, 钩手水母复杂的生活史、扩散能力、地理隔离和海流分布可能是影响钩手水母遗传结构的重要因素。

Population genetic structure of Gonionemus vertens based on the mitochondrial COI sequence

Gonionemus vertens is widely distributed throughout the Atlantic and Pacific Oceans and is one of venomous jellyfish species in China. To investigate the population genetic structure of G. vertens, we sequenced the mtDNA COI gene in 104 individuals collected from four geographic locations along the coast of the Yellow Sea and the Bohai Sea, and the homologous sequences of other 182 individuals which were obtained from GenBank were also analyzed. A total of 52 polymorphic nucleotide sites were detected among the 286 individuals, which defined 14 haplotypes. The overall haplotype diversity and nucleotide diversity were 0.743 ± 0.012 and 1.046% ± 0.097%, respectively. Compared with several other giant jellyfish species, the genetic diversity of G. vertens was at the higher level. AMOVA analysis indicated that extremely significant difference existed among the groups, within populations and among the populations within groups, with 60.17% molecular variation among the groups, 13.37% molecular variation within populations, and 26.46% molecular variation among the populations within groups. Pairwise fixation index (F_st) values showed that significant population structure existed between the G. vertens population collected in Xiamen waters with other populations collected from Laoting, Dongying, Yantai, and Dalian waters, and the population structure throughout Dalian with Dongying, or with Yantai were also significant. Phylogeographic analysis of the COI region revealed two lineages. The results indicated that the complex life cycle characteristics, dispersal ability, geographic isolation, together with the prevailing ocean currents in this region, may be important factors influencing the genetic structure of G. vertens.