基于线粒体DNA三种基因序列探讨青蟹属的系统发育关系

Phylogenetic relationships of four Scylla species based on three kinds of mitochondrial sequences

青蟹属(Scylla)分为4个种的观点得到了大多数学者的支持,但由于分析方法和采用序列的差异,种间系统发育关系仍然没有解决。本文对青蟹属4种24个体的线粒体12S rRNA、16S rRNA和COI基因部分序列进行了测定。对3种序列拼接后,根据不同进化速率采用分组策略,分别以贝叶氏法和最大似然法构建青蟹属的系统进化树并与Neighbor Joining(NJ)树进行比较。结果显示,3种进化树都获得完全一致的拓扑结构,其中贝叶氏法和最大似然法都强烈支持拟穴青蟹S.paramamosain与紫螯青蟹S.tranquebarica是姐妹种(自举值为95%,贝叶氏法后验概率为1.0)。锯缘青蟹S.serrata分化早于拟穴青蟹和紫螯青蟹,为它们的姐妹种(自举值等于60%,贝叶氏法后验概率等于0.95);榄绿青蟹S.olivacea是4种青蟹中最早分化出来的种类。本文明确了青蟹属物种间系统发育关系,为澄清我国青蟹的分类地位进一步提供了分子依据。

Most research supports the idea that there are four species in genus Scylla.Their phylogeny,however,has not been fully understood,especially the interrelationships among S.serrata,S.paramamosain and S.tranquebarica.We analyzed the sequences of 12S rRNA,16S rRNA and COI gene in all four species of genus Scylla and established the phylogenetic tree by using Bayesian,Maximum Likehood（ML）,and Neighbor Joining（NJ） approaches after the sequences were concatenated and partitioned.All three methods produced the same topology.The sister-group relationship between S.paramamosain and S.tranquebarica was highly supported by both Bayesian and ML approaches,with bootstrap value of 95% and Bayesian posterior probability of 1.0.S.serrata was the sister group of S.paramamosain and S.tranquebarica（bootstrap = 60%,Bayesian posterior probability = 0.95）,while S.olivacea was found as the basal group to the other three species.The phylogenetic interrelationships among the four species of genus Scylla were uncovered in this study,which may provide molecular evidence for classification of genus Scylla.