基于线粒体COI基因的海蜇不同地理群体遗传特征

对采自辽东湾和韩国江华岛的2个海蜇群体56个个体的线粒体COI基因序列进行扩增,并结合GenBank上其他15个海蜇样品的同源序列对其进行序列变异分析,研究海蜇群体的遗传特征和群体遗传结构状况.在所分析的71个个体中共检测到28个多态位点,定义了32种单倍型.海蜇群体呈现出高的单倍型多样性(0.91±0.06～0.94±0.01)和中等或较低的核苷酸多样性(0.60±0.34)%～(0.68±0.40)%].与其他几种大型水母相比,海蜇群体的遗传多样性水平较高.系统分析结果显示,海蜇群体间具有2个明显的单倍型谱系分支.比较海蜇不同群体间的遗传分化指数(F_ST)和分子变异分析(AMOVA)发现,在本研究取样范围内不同海蜇群体间存在明显的遗传结构.不同海蜇群体存在复杂的遗传模式,海蜇独特的生活史特征、其分布海域的海流状况及人为因素如增殖放流等可能是造成海蜇这种复杂遗传模式的原因.

Genetic characterization of different populations of Rhopilema esculentum based on the mitochondrial COI sequence.

To investigate the genetic characterization and population genetic structure of Rhopilema esculentum, we sequenced the mtDNA COI gene (624 bp) in 56 individuals collected from Liaodong Bay and the Ganghwado Island in the estuarine waters of the Han River. In addition, the homologous sequences of other 15 individuals which were sampled from the Bohai and Yellow seas and Sea of Japan were analyzed. A total of 28 polymorphic nucleotide sites were detected among the 71 individuals, which defined 32 haplotypes. Haplotype diversity levels were high (0.91±0.06-0.94±0.01) in R. esculentum populations, whereas those of nucleotide diversity were moderate to low (0.60±0.34)%-(0.68±0.40)%]. Compared with several other giant jellyfish species, the variation level of R. esculentum was high. Phylogeographic analysis of the COI region revealed two lineages. The pairwise F_ST comparison and hierarchical molecular variance analysis (AMOVA) showed that significant population structure existed throughout the range of R. esculentum. The results of this study indicated that the life-cycle characteristics, together with possible anthropogenic introduction such as stock enhancement and the prevailing ocean currents in this region, were proposed as the main factors that determined the genetic patterns of R. esculentum.