5种石斑鱼核糖体DNA ITS1序列及其分子系统进化关系

摘要

为了明确分布于中国海域点带石斑鱼(Epinephelus malabaricus)、青石斑鱼(E. awoara)、巨石斑鱼(E. tauvina)、六带石斑鱼(E. sexfasciatus)和宝石石斑鱼(E. areolatus))等石斑鱼属(Epinephelus)鱼类的系统发育关系，作者采用PCR和DNA测序技术，测定了5种石斑鱼属鱼类的核糖体DNA ITS1序列，获得其ITS片段长度分别为537、536、535、528、532 bp。研究结果表明：5种石斑鱼rDNA ITS1序列的碱基组成趋势相似， A+T含量皆低于C+G含量， A+T含量最低为宝石石斑鱼(37.6％)，最高为六带石斑鱼(41.5%)；基于Kimura-2双参数模型计算得到上述石斑鱼种间遗传距离在0.0000~0.3002。基于MP法、ML法和NJ法构建的3种分子系统树表明， rDNA ITS1序列与形态呈同步进化关系，宝石石斑鱼与其他4种石斑鱼的亲缘关系较远，表明在所研究的物种中最早分化而出，而点带石斑鱼与青石斑鱼的亲缘关系最近，分化的时间最晚。%In order to explore the phylogenetic relationship among 5 endemic species of groupers,Epinephelus malabaricus, E. awoara,E. tauvina,E. sexfasctaius, andE. areolatus in China Sea. The sequences of rDNA ITS1 were analyzed and their lengths were determined to be 537, 536, 535, 528 and 532 bp respectively. The results were as follows: The basic composition of rDNA ITS1 sequences of 5 kinds of groupers was close to each other. The A+T component was lower than C+G component. A+T was the lowest (37.6%) inE. areolatus and the highest (41.5%) inE. sexfasctaius. The genetic distance measured using the kimura-two parameter model was from 0.0000 to 0.3002 in 5 kinds of groupers. The cluster result of 5 kinds of groupers in molecular phylogenetic trees constructed using MP, ML and NJ method were identical, suggesting that rDNA ITS1 sequences and morphological evolution might be synchronous. In 5 kinds of groupers,E. areolatus showed far away from other 4 species, suggesting that theE. areolatus might differentiated earlyfrom other species. WhileE. malabaricus showed nearest toE. awoara, suggesting that this species could be differentiated later.