三种琥珀螺(Succineidae)基于DNA条形码技术的分类分析

琥珀螺科的传统分类研究主要基于形态特征,由于壳相特征的趋同性以及比较形态解剖学研究基础的不足,中国琥珀螺科系统分类有待深入研究,已报道属种有待厘定。本研究运用DNA条形码技术,对新疆11个地点3种琥珀螺(Succinea daucina,Oxyloma wujiaquensis,Oxyloma sp.)的线粒体COⅠ与16S rRNA基因序列进行分析,并对三者的分类关系进行探讨。通过测序共获取COⅠ(640 bp)与16S rRNA(418 bp)基因序列各69条,其碱基组成均显示出较高的A+T比例(COⅠ:67.91%,16S rRNA:73.15%),与目前已知琥珀螺线粒体DNA序列特征相符。基于Kimura双参数模型计算:3种琥珀螺的COⅠ基因序列(640 bp)平均种间遗传距离为0.1356~0.1713,平均种内遗传距离为0.0068~0.0092;16S rRNA基因序列(418 bp)平均种间遗传距离为0.0793~0.1481,平均种内遗传距离为0.0034~0.0089;3种琥珀螺COⅠ与16S rRNA基因的种间遗传变异均远大于种内遗传变异,存在明显的间隔。采用最大似然法构建分子系统树,结果显示本研究中不同地点的3种琥珀螺分别聚为置信度较高的分支,均有大于95%的支持度。本研究基于DNA条形码技术的分类研究结果与形态学研究结果一致。综上结果表明,COⅠ与16S r RNA基因适用于琥珀螺的物种鉴定。

Classification of Three Succineidae Species Based on DNA Barcoding Approach

The traditional classification and taxonomy of Succineidae are mainly based on morphological characters.Because of little diversity and considerable convergence on shell characters,and insufficient study in morphology,the validity of many of records in China is questionable.In the present study,the gene sequence features(COⅠand 16S rRNA)and the classification of three Succineidae species(Succinea daucina,Oxyloma wujiaquensis and Oxyloma sp.)from 11 locations in Xinjiang were investigated by using DNA barcoding approach.69(640 bp)COⅠgene and 69(418 bp)16S rRNA gene sequences were got by PCR.The base composition of both gene sequences showed a high A+T ratio(COⅠ:67.91%,16S rRNA:73.15%),which was consistent with mitoch-ondrial DNA sequence composition of other Succineidae.Based on Kimura-2 parameter calculation,that the inter-specific COⅠdivergence was 0.1356~0.1713,and intra-specific COⅠvariation was 0.0068~0.0092;the inter-specific 16S rRNA divergence was 0.0793~0.1481,and intra-specific 16S rRNA variation was 0.0034~0.0089.Inter-specific divergence of both genes was greatly larger than intra-specific variation in this study.An obvious'barcoding gap'was detected for three species in both markers.The result of phylogenic maximum likelihood analysis were basically consistent with that of morphological identification,and three species from different locations tested in this study were gathered in three different clades with high bootstrap values(95%).Our results indicated that COⅠand 16S rRNA genes appeared to be accurate and efficient markers for Succin-eidae species identification in Xinjiang,but for the phylogenetic analysis of Succineidae,more information from more areas,more species,more gene markers and more morphological data were wanted.