中国东南沿海青蟹线粒体COI基因部分序列分析

对我国东南沿海5个地区的72个青蟹个体的线粒体细胞色素氧化酶亚基I (COI)部分序列序列进行了测定和分析。获得的72个细胞色素氧化酶亚基I (COI)序列可分为12个单倍型，与GenBank中已知的Scylla paramamosain COI序列的相似性达到98%以上，与其它3种 青蟹的差异为7.36%～15.54%。这些序列与S. paramamosain的遗传距离仅为0.00783，但是与S. serrata、S. olivacea和S. tranquebarica〗的遗传距离却分别达到0.11659、0.17812和0.08423。序列特征、遗传距离和系统进化等分析结果都表明本文研究的青蟹为S. paramamosain。结果提示，在进行青蟹属相关研究应当仔细鉴别采集样本的种类。

Sequence analysis of mitochondrial COI gene of Scylla spp. along coast of southeastern China

Culture of mud crab (genus Scylla) as precious seafood is growing rapidly in China recently. However, the taxonomy of mud crab in China is still in controversial. Mitochondrial cytochome oxidasesubunit I (COI) gene was used to identify species of genus Scylla resided along coast of southeastern China. A fragment of the COI gene was amplified and sequenced from 72 Scylla spp. individuals obtained from 5 regions along coast of southeastern China. 12 distinct haplotypes, which were identified among 72 COI sequences, were above 98% identical to the known S. paramamosain COI gene sequences, and showed 7.36%-15.54% difference from other 3 species. The average genetic distance of COI sequences between these individuals and S. paramamosain is only 0.00783 and this does not significantly differ from the intraspecific distance, while between these individuals and S. serrata, S. olivacea and S. tranquebarica is 0.11659, 0.17812 and 0.08423 respectively. The NJ tree shows that all four species formed reciprocal monophyletic groups, with the S. olivacea located in the base, and S. olivacea closely related to S. tranquebarica. Four species of Scylla are delineated as four well supported groups, with average levels of interspecific sequence difference (-12%) more than six times greater than that observed at the intraspecific level (-2%) and 12 haplotypes identified in this study cluster closely with the known COI sequences from S. paramamosain. The results of sequence characterization, genetic distance and phylogenetic analysis suggest that all samples investigated should belong to S. paramamosain and S. paramamosain should be one of the most common species in China. Caution is called for species identification when studying Scylla.