中国北方习见水母类的DNA条形码分析

摘要

Sixty-two mtCOI sequences were determined for 22 medusozoa species sampled from the northern Chinese inshore regions. Two hundred and seven sequences, including 164 additional mtCOI genes from GenBank were compared to test the utility of this molecular marker for species identifications. The intraspecific variation of the gene ranged from 0 to 7.4% （p-distance）, with the average of 0.9% （SD=0.014）. More than 93% the pairwise comparisons gave the divergence smaller than 4%. Meanwhile, the counterpart between species within the same genera ranged from 5.4% （Sarsia） to 44.9% （Lensia）, with the average of 25.1% （SD=0.118）. More than 97% of the variations were larger than 10%. For all the species collected in China, no overlap was observed between the variations within and among species. In conclusion, the barcode gap, which ensured that eoxl sequences can be used as reliable characters for species identification, can be determined in our study. Monophyly of each species was resolved in a neighbour joining tree based on mtCOI genes, which confirmed the efficiency of mtCOI for species identification. The proposals to conserve jellyfish samples were tested. No candidate pro- tocol could keep morphologial keys for species identification for a long time. However, DNA conserver solution was pre- ferred owing to its better performance on maintaining both molecular and morphological features. Furthermore, the tax- onomies of blooming jellyfishes in China were checked using DNA barcodes.%本研究获得了中国北方近海习见水母类24个种共62条线粒体细胞色素C氧化酶亚基I（mtCOI）序列，结合GenBank中具DNA条形码关键词的mtCOI序列，共比较了水母类mtCOI片段207条，水母mtC01种内遗传差异在0％-7．4％之间，均值为0．9％（SD=0．014），其中约93％的个体种内差异小于4％；近源种间遗传差异在5．4％（Sarsia）到44．9％（Lensia）之间，均值为25．1％（SD=0．118），97％以上的个体种间遗传差异大于10％。绝大多数（98．8％）水母种类种内遗传差异小于种间遗传差异，条形码间隙明显。本研究涉及的中国北方习见水母种内遗传差异均显著小于种间遗传差异，结果表明以mtCOI作为DNA条形码可以实现对中国北方习见水母种类鉴定。利用DNA条形码序列分析，梳理了中国近海一些常见水母的分类地位。此外，对4种保存液保存方法的比较研究表明，90％乙醇、DMSO、RNASafer和DNAConserver4种保存液无法同时保存形态学特征和DNA序列，但DNAConserver的效果相对较好。