基于mtCOI片段序列的南极海域浮游动物DNA条形码研究

DNA BARCODING OF ANTARCTIC MARINE ZOOPLANKTON FOR SPECIES IDENTIFICATION AND RECOGNITION

极地海区浮游动物对全球气候变化的响应极其敏感,其群落结构已成为研究全球变化对海洋生态系统影响的重要指标,而DNA条形码则是浮游动物种类鉴定的有效工具。采用线粒体细胞色素c氧化酶第一亚基编码基因(mtCOI)特异扩增测序的方法,分析了南大洋32种常见浮游动物的94条DNA条形码序列,其长度分布在830碱基到1050碱基之间。发现南极常见浮游动物种内遗传差异均值为0.67%,分布在0—2.6%之间;同属近源种间遗传差异均值为14.3%,分布在0.1%—29.3%之间。哲水蚤属的近缘哲水蚤(Calanus propinquus)和C.simillimus遗传相似度非常高。考虑到上述两者在形态和遗传上的相似性,本研究认为两种可能为同种异名,有待开展深入研究确认C.simillimus种的地位。除了哲水蚤属的两种外,所有样品种内、种间遗传差异显著,且同种的不同样品都聚到一起形成单系群。结果表明mtCOI序列可以作为DNA条形码实现南极浮游动物常见种的准确鉴定(水母和海樽等胶质浮游动物的有效性未验证)。以上结果也得到了示踪向量分析的证实。本研究新增的DNA条形码数据以及新提供的兼并引物必将推动南极浮游动物环境样品的宏基因组学研究。

Polar zooplankton are particularly sensitive to climate change,and have been applied as‘rapid-responders＇ of climate-induced change in this fragile ecosystem.DNA barcoding provides an alternative approach for rapid species identification of zooplankton in the Southern Ocean,which will accelerate the routine monitoring of zooplankton community structure.Ninety-four specimens belonging to 32 Antarctic zooplankton were barcoded to provide a more comprehensive reference library.An 830 to 1050 base-pair region of the mitochondrial cytochrome c oxidase subunit I（mtCOI） gene was obtained as a DNA barcode.The intraspecific variation of the gene ranged from 0 to 2.6%（p-distance）,with an average of 0.67%（SD =0.67%）.The counterpart between species within the same genera ranged from 0.1%（Calanus） to 29.3%,with an average of 15.3%（SD = 8.4%）.The morphological and genetic similarities between C.propinquus and C.simillimus raise new questions about the status of C.simillimus as a different species.With the exception of the two Calanus species（C.propinquus and C.simillimus）,the intraspecific genetic divergence was much smaller than interspecific divergence among the congenus species,confirming the existence of a barcode gap for Antarctic zooplankton.In addition,all species clustered into a monophyletic clade except for Calanus species.Hence,DNA barcoding is confirmed as an accurate and efficient approach for zooplankton identification in the Southern Ocean（species belonging to jellyfish and doliolum were not tested）.Confirming evidence was also provided by indicator vector analysis.The new primer sets issued here will facilitate study of the species composition of Antarctic marine zooplankton by single-gene based environmental metagenomic analysis.