高鳍带鱼遗传变异及与近缘种间的系统进化关系

GENETIC VARIATION OF TRICHIURUS LEPTURUS AND PHYLOGENETIC RELATIONSHIP AMONG ITS CLOSED SPECIES

高鳍带鱼Trichiurus lepturusLinnaeus,1758分布广泛、形态多变,与近缘种间辨别困难,在其种群鉴别、物种分类及系统进化上争议较大。本项研究通过测定采自海南三亚外海高鳍带鱼疑似种11个个体的线粒体16S rRNA基因部分序列,结合已报道的该物种其它地理种群及其近缘种的同源序列,采用生物软件对碱基组成和序列变异进行分析,计算Kimura双参数净遗传距离和分歧时间,进行分子变异分析(AMOVA)和分化固定指数(FST)计算,并以小带鱼Eupleurogrammus muticus为外群构建NJ、ML系统树,综合探讨世界范围内高鳍带鱼的遗传变异及与近缘种间的系统进化关系。根据所得分子数据并结合形态学研究结果得出如下结论:1)采自海南三亚外海的带鱼是高鳍带鱼T.lepturusLinnaeus,1758,该物种在中国南海和东海南部有分布;2)海南三亚外海、非洲西岸和大西洋西岸的高鳍带鱼是同一个物种的3个地理种群,彼此间遗传分化显著;3)高鳍带鱼是带鱼属中最新演化的种类,与日本带鱼T.japonicus、带鱼未定种Trichiurussp.2具有较近的亲缘关系;短带鱼T.brevis则是比它们原始的种类。

The population identification,taxonomic classification and phylogenetic relationship of large head hairtail Trichiurus lepturus Linnaeus,1758（Perciformes,Trichiuridae）is controversial because of variable morphology and widely distribution.In this study,the mtDNA 16S rRNA gene fragment of 11 hairtail fishes caught off the coast of Sanya,Hainan Province（South China Sea）were amplified using PCR techniques.And the homologous sequences of Trichiurus species from previous studies were also included in the comparative analysis.Genetic information indexes,including base composition,sequence variation and Kimura-2 parameter net genetic distance,were generated by using a suite of biology software.Hierarchical molecular variance analysis（AMOVA）and the fixation index（FST）were also calculated among populations of T.lepturus.Phylogenetic analysis using neighbor-joining（NJ）and maximum-likelihood（ML）methods with Eupleurogrammus muticus as outgroup.Conclusions were drawn as follows：1）the hairtail fishes caught off the coast of Sanya were identified as T.lepturus Linnaeus,1758 based on sequence comparative analysis;it occurs in the South China Sea and Southern East China Sea;2）the T.lepturus obtained from the coast off Sanya,West African coast and Western Atlantic represented three geographic populations within the same species,although a significant genetic differentiation was found among populations;3）T.lepturus is the most recently diverged species,which showed close relationship with T.japonicus and Trichiurus sp.2;T.brevis is more primitive than above three species.