中国裸胸鳝属10种鱼类分子系统发育关系的16SrDNA分析

为了阐明南中国海裸胸鳝属(Gymnothorax)鱼类系统进化情况,利用聚合酶链式反应扩增目的产物,将其连接到T载体后,并对其序列进行测定,共得到9种裸胸鳝属鱼类线粒体16S ribosomalDNA(16S rDNA)基因的部分序列,采用多个生物软件对序列变异和碱基组成进行分析,计算了Kimura2-parameter遗传距离,转换/颠换比等遗传信息指数,下载基因库中16SrDNA基因的同源序列,以鳗鲡属(Anguilla)的花鳗鲡(Anguilla marmorata)为外群构建NJ(Neighbore-Joining)、MP(MaximumParsimony)和ME(Minimum Evolution)系统进化树。根据所得分子数据并结合形态学特征推论如下:(1)在所研究的10种裸胸鳝鱼中共有516个位点、其中143个核苷酸位点存在变异(27.7%);(2)序列变异的转换/颠换比值的平均值为3.441;相对遗传距离数据表明斑颈裸胸鳝(G. margaritophorus)和网纹裸胸鳝(G. reticularis)差异最大(0.177),褐祼胸鳝(G. hepaticus)与布雷顿氏裸胸鳝(G. breedeni)差异最小(0.022);(3)NJ树、ME树表明裸胸鳝属内部存在3个平行进化的姐妹分支,分支内部的种类组成与地理分布无关。

Analysis of the molecular phylogenetic relationships of 10 Gymnothorax species from China Seas based on 16S rDNA fragment sequences

In order to evaluate the phylogenetic relationship of the Gymnothorax from the China Seas, the 16S ribosomal DNA of nine Gymnothorax species were amplified using PCR techniques through connecting the desired fragments to the T vector. 516 bp DNA fragments were obtained and the sequences were analyzed. The sequence variation, base composition and genetic information indexes, including Kimura-2 parameter genetic distance and Ts/Tv ratios, were generated using a suite of biology software. The 16S rDNA genes homologous sequences of Gymnothorax were downloaded from GenBank and NJ (Neighbore-Joining), MP (Maximum Parsimony) and ME(Minimum Evolution) trees were built through biological software based on these sequences and morphological characteristics of Gymnothorax. Conclusions were drawn as follow: (1) Of the 516 aligned base pairs of ten Gymnothorax fishes studied, 143 nucleotide sites were variable, comprising 27.7% of the total base pairs. (2) It was 3.441 of the average transition/transversion ratio among all pair wise comparisons. The maximum pairwise nucleotide divergence value among all taxa was 0.177 between G. reticlaris and G. margaritophorus, and the minimum value was 0.022 between G. hepatcus and G. breedeni. (3) There are three parallel evolutionary sister clades existing (with high bootstrap value support) in Gymnothorax based on NJ trees, ME trees. The species within three clades seem to be irrelevant to their biogeographic distributions.