中国蚌科线粒体16S rRNA序列变异及系统发育

首次测定了中国淡水贝类———蚌科 (Unionidae) 1 3个属代表种类的线粒体 1 6SrRNA部分序列。用Clustal X排序软件进行 1 6SrRNA序列的对位排列 ,序列总长度为 30 5— 32 0bp。通过Mega 2 0软件对所得线粒体 1 6SrRNA片段序列进行比较 ,共发现 1 0 8个碱基存在变异 ,其中包括 77个简约信息位点 ,并用“Pairwisedistance”计算了各属间的相对遗传距离。以贻贝为外类群 ,采用Mega 2 0软件中的“Neighbore Joining”法得到惟一一个分子系统树 ,系统树各分支的置信度由“Bootstrap”1 0 0 0循环检验。结果表明 :分布于中国的蚌科形成三个明显的类群 ,第一个类群 ,包括帆蚌属、蛏蚌属、丽蚌属和尖锄蚌属 ;第二个类群 ,由矛蚌属、扭蚌属、裂脊蚌属、鳞皮蚌属、尖嵴蚌属、楔蚌属和珠蚌属组成 ;第三个类群只包括无齿蚌和冠蚌两个属。由此可以看出 ,它们有可能分别隶属于三个不同的亚科 ,即小方蚌亚科 (帆蚌属、蛏蚌属、丽蚌属和尖锄蚌属 )、无齿蚌亚科 (无齿蚌属和冠蚌属 )和珠蚌亚科 (矛蚌属、扭蚌属、裂脊蚌属、鳞皮蚌属、尖嵴蚌属、楔蚌属和珠蚌属 ) ,由此证明小方蚌亚科在中国的存在 ,并且 ,对几个属的分类位置作了调整。其中鳞皮蚌属和蛏蚌属原来属于无齿蚌亚科 ,根据线粒体 1 6SrRNA的结果 ,前者应该放

PHYLOGENY OF THE UNIONIDAE BASED ON PARTIAL MITOCHONDRIAL 16S rRNA SEQUENCES

This study presents the mitochondrial 16S rRNA partial sequences representing 13 genera of Chinese freshwater mussel Unionidae. Alignments were conducted with the help of Clustal X.After alignment,there were 305-320 sites. Sequence variations were analyzed with Mega 2.0 software,one hundred and eight sites were variable,among which there were seventy seven phylogenetically informative sites."Pairwise distances" were computed among the 13 genera with Mytilus edulis designated as outgroup. Only one molecular phylogenetic tree was obtained using Neighbore Joining method of Mega 2.0. The bootstrap analyses (1000 replications) were performed to test the confidence of nodes. According to our results,Unionidae recorded from China group to three clades: a basal Hyriopsis + Solenaia + Lamprotula + Ptychorhynchus clade,an Acuticosta + Unio + Arconaia + Cuneopsis + Lanceolaria + Schistodesmus + Arconaia calde and an Anodonta + Cristaria clade. Therefore,Chinese unionids should be divided into three subfamilies: Ambleminae( Hyriopsis + Solenaia + Lamprotula + Ptychorhynchus ),Anodontinae( Anodonta + Cristaria ) and Unioninae ( Acuticosta + Unio + Arconaia + Cuneopsis + Lanceolaria + Schistodesmus + Arconaia ),which also demonstrates the existence of Ambleminae in China. Thereinto,the analysis of mitochondrial 16S rRNA indicates that Solenaia and Lepidodesma ,which were placed Anodontinae before,should be moved to the subfamily Ambleminae and Unioninae respectively. To more accurately reflect the phylogeny, Hyriopsis,Lamprotula and Ptychorhynchus should be moved to the subfamily Ambleminae.