从细胞色素b部分序列探讨石斑鱼属的分子系统发育关系

MOLECULAR PHYLOGENETIC RELATIONSHIP OF EPINEPHELUS BASED ON SEQUENCES OF MTDNA CYTB

石斑鱼的分类在学术界尚存在很多争议。本文采用PCR技术,测定了分布于中国的点带石斑鱼(Epinepheluscoioiaes)、青石斑鱼(E.awoara)、六带石斑鱼(E.sexfasciatus)、褐石斑鱼(E.brunneus),长棘石斑鱼(E.longispinis),吻斑石斑鱼(E.spilotoceps),巨石斑鱼(E.tauvina)以及石斑鱼亚科侧牙鲈属的侧牙鲈(Variola louti)的线粒体细胞色素b基因402bp的序列,结合GenBank提供的7种中国无记录的石斑鱼:青铜石斑鱼(E.aeneus)、海丰石斑鱼(E.haifensis)、犬牙石斑鱼(E.caninus)、东大西洋石斑鱼(E.marginatus)、白斑石斑鱼(E.multinotatus)、德氏石斑鱼(E.drummondhayi)、淡点石斑鱼(E.labriformis),把这14种石斑鱼作为内群,对他们的序列组成和结构特点进行了分析;并以同为科(Serranidae)、石斑鱼亚科(Epinephelinae)的侧牙鲈属(Variola)的侧牙鲈作外群,分别用MP法、NJ法对内、外群构建了分子系统树,结果表明:(1)14种石斑鱼402bp的mtDNA Cytb部分序列的碱基组成上,A+T的含量为53.6%高于G+C含量(46.4%),序列中转换颠换比为4.78,没有突变饱和;(2)青石斑鱼与六带石斑鱼、点带石斑鱼与巨石斑鱼、长棘石斑鱼与吻斑石斑鱼分别聚在一起,与形态分类结果一致;(3)系统树中,大西洋与太平洋种类各枝交替汇合,表明石斑鱼的Cytb序列有严格的保守性,也可能是协同进化的结果;(4)揭示在良种选配或遗传管理时,避免居于同枝的石斑鱼混交,将大西洋种类与太平洋种类杂交可能是遗传改良的一种途径。

The sequences （402bp） of mtDNA Cyt b were sequenced for such seven endemic species of groupers as Epinephelus awoara , E. brunneus , E. coioides , E. longispinis , E. sexfasciatus , E. spilotoceps and E. tauvina in China. The mtDNA Cyt b sequences of other seven foreign species of groupers, e . g. , E. aeneus , E. caninus , E. druramondhayi , E. haifensis , E. labriformis, E. marginatus and E. multinotatus from GenBank were combined and analysed as ingroup, and Variola/outi was used as outgroup. The two types of molecular phylogenetic trees were based on the sequences of 15 species with maximum parsimony method （MP） and neighbor-joining method （NJ） respectively. The results were as follows：（1） As to base constitution of mtDNA Cyt b sequence （402bp） of 14 kinds of Epinephelus, the content of （A ＋ T） is 53.6%, higher than that of （G ＋ C） （46.4%）. The transition/transversion ratio is 4.78 with no mutation saturation. （2） The cluster relationships between E. awoara and E. sexfasciat, E. coioides and E. tauvina , E. longispinis and E. spilotoceps respectively are consistent with phenotypes in taxono- my. （3） In the system tree, the species in Atlantic Ocean associate closely with those in Pacific Ocean, which suggests that the Cyt b sequences of Epinephelus express strict conservation and may be the result of coordinate evolution. （4） In well-bred mating or heredity management, mixing mating of Epinephelus of the same branch should be avoided. It is likely to be an effective way to mate the species of Atlantic Ocean with those of Pacific Ocean in order to improve the inheritance species.