东海近岸带鱼(Trichiurus japonicus)线粒体控制区序列的群体遗传变异研究

带鱼(Trichiurusjaponicus)是广泛分布于东亚大陆架海域的暖温性近底层经济鱼类,也是东海区最重要的海洋渔业捕捞对象。然而,目前的研究报道对东海近岸带鱼群体遗传变异特性认识不足,不利于其种群的遗传资源保护和管理。本研究利用线粒体控制区序列对东海近岸带鱼6个群体191个个体的遗传多样性、遗传分化和历史动态进行分析。在577 bp长的控制区序列中共检测到70个多态位点,定义了121个单倍型。群体总的单倍型多样性较高(0.9911),但总的核苷酸多样性较低(0.0092),群体间遗传多样性水平差异较小。单倍型遗传学关系、Fst值和分子方差分析结果均表明群体间的遗传分化不显著,存在广泛的基因交流。历史动态分析结果表明东海近岸带鱼群体在更新世中晚期可能经历了瓶颈效应和随后的群体快速扩张,这是导致群体遗传多样性较低的主要原因。带鱼较强的扩散能力、洄游行为、海洋环流以及近期的群体扩张可能是造成东海近岸带鱼缺乏显著的系统地理种群结构的原因。研究结果提示,在线粒体DNA水平上,东海近岸带鱼群体是一个随机交配的种群,在遗传资源管理上可作为一个单元进行管理。

STUDY ON POPULATION GENETIC VARIATION OF TRICHIURUS JAPONICUS IN NEARSHORE OF THE EAST CHINA SEA IN MITOCHONDRIAL CONTROL REGION SEQUENCES

The hairtail Trichiurus japonicus, a common species in the tropical and warm-temperate waters of the East Asian continental shelf, is an economic fish and has become the most important target species of marine fishery in the East China Sea. However, there is a lack of understanding on the genetic variation of T. japonicus population in nearshore of the East China Sea, which is not conducive to the conservation and management of the population genetic resources. In this study, genetic diversity, genetic differentiation, and historical demography of six T. japonicus populations from nearshore of the East China Sea were analyzed based on the 191 mitochondrial control region sequences. A total of 70 polymorphic sites were detected in the 577 bp length of control region sequence, from which 121 haplotypes are defined. The total haplotype diversity of population was higher (0.9911), but the total nucleotide diversity was lower (0.0092), and there was no significant difference in genetic diversity among the populations. The genetic relationships of haplotypes, pairwise F_st values, and hierarchical molecular variance analysis (AMOVA) showed no significant genetic difference among the populations, indicating a high gene flow among them. Historical demography analysis showed that T. japonicus in nearshore of the East China Sea may have experienced population bottleneck during middle and late Pleistocene and subsequent sudden population expansion. This is the main reason for the low genetic diversity of the populations. Factors such as high dispersal capacity, migration behavior, ocean circulation, and recent population expansion could be responsible for the lack of signification phylogeographic population structure of T. japonicus. Therefore, we suggest that T. japonicus from nearshore of the East China Sea constituted a panmictic population at the level of mitochondrial DNA and can be treated as a unit in the management of genetic resources.