中华虎头蟹线粒体16S rRNA和 COⅠ基因的序列比较及其系统进化分析

Sequence comparison and phylogenetic analysis of mtDNA 16S rRNA and COⅠ gene sequences in Orithyia sinica

为研究中华虎头蟹野生群体的种质资源及遗传多样性状况,采用PCR扩增获得中华虎头蟹线粒体DNA的16S rRNA和COⅠ基因片段,分别对其进行序列比较及系统进化分析。16S rRNA和COⅠ基因片段的A+T平均含量分别为67.7%和61.4%,A+T含量显著高于G+C含量。长度为515 bp的16S rRNA基因片段共检测出单倍型4种,多态性位点4个,均为单一变异位点;长度为653 bp的COⅠ基因片段共检测出单倍型11种,多态性位点23个,其中简约信息位点5个和单一变异位点18个。COⅠ基因片段比16S rRNA基因片段具有较大的变异,更适于中华虎头蟹种群的遗传多样性分析。基于16S rRNA和COⅠ基因片段的遗传距离与系统进化分析结果一致,表明中华虎头蟹与梭子蟹科的蟹类亲缘关系最近,方蟹科与沙蟹科的蟹类聚为一支,与传统分类结果基本一致;而脊椎动物2个基因片段的系统进化分析结果不一致。根据16S rRNA基因片段的遗传距离推测出4科7种蟹的大致分化时间发生在古新世至始新世。

To study the germplasm resources and genetic diversity in the wild population of Orithyia sinica,the mitochondrial DNA 16S rRNA and COⅠ gene sequences were obtained from O.sinica wild populations by PCR amplification.A T base content of 16S rRNA and COⅠgene sequences were 67.7% and 61.4%,respectively,which were significantly higher than G C base content.From 515 bp of 16S rRNA gene sequences,4 haplotypes and 4 polymorphic sites were detected,and they were all singleton variable sites.As for 653 bp of COⅠ gene sequences,11 haplotypes and 23 polymorphic sites were detected,including 18 singleton variable sites and 5 parsimony informative sites.COⅠ gene sequences have more variations than 16S rRNA gene sequences,indicating that COⅠ gene sequences were suitable for analysis of genetic diversity of O.sinica.The results of genetic distances and phylogenetic analysis of 16S rRNA and COⅠ gene sequences were consistent with each other,showing that O.sinica have much closer relationship with crabs of Portunidae,and crabs of Grapsidae were together with that of Ocypodidae,which were consistent with classical taxonomy.Differentiation time of 11 species of crabs and vertebrates was deduced based on the genetic distance of 16S rRNA gene sequences,and the results showed that the radiation differentiation time of four families of crabs was between Paleocene and Eocene.This study is expected to provide important information for the protection and utilization of O.sinica resources of China.