中文摘要：

综合分析了软骨鱼10个物种的线粒体基因组全序列,全面揭示软骨鱼线粒体基因组的基本特征、蛋白质编码基因和差异位点等。软骨鱼10个物种线粒体基因组均编码后生动物标准的37个基因,而且其基因排列完全相同。真鲨目和鳐形目线粒体基因组的13个蛋白质编码基因的Ka/Ks比值都远远低于1（0.019 1~0.156 4）,显示出较强的纯化（负）选择。基于线粒体基因组构建的系统发育树结果显示,软骨鱼纲分为两支：全头亚纲和板鳃亚纲。在板鳃亚纲内部,鳐形目和鲼形目聚为一支;真鲨目、鼠鲨目、须鲨目、虎鲨目和角鲨目聚为一支,其亲缘关系为：{[（真鲨目＋鼠鲨目）＋须鲨目）]＋虎鲨目}＋角鲨目。软骨鱼线粒体基因组差异位点分析表明,在软骨鱼群体遗传的研究中,nad5和nad4基因是理想的分子标记,可以作为cox1基因辅助的分子标记,用于分析软骨鱼不同群体之间的遗传多样性,为其生物多样性的保护及合理利用其生物资源提供更多保障。

英文摘要：

The basic characteristics of chondrichthyes mitochondrial genomes were fully revealed by comprehensive analysis of mitochondrial genomes in ten cartilaginous fishes.Mitochondrial genomes of cartilaginous fishes contain 37 standard metazoan genes and their gene order is identical.The Ka/Ks ratio of 13 mitochondrial protein-coding genes in the Carcharhiniformes and Rajiformes classes is much lower than 1（0.019 1~0.156 4）,indicating a strong purifying selection（negative selection）.The phylogenetic trees based on mitochondrial genomes showed that the class Chondrichthyes is divided into two clades： the subclass Holocephali and the subclass Elasmobranchii.Inside the subclass Elasmobranchii,the order Rajiformes and the order Myliobatiformes were clustered as a clade,and the other five orders（Carcharhiniformes,Lamniformes,Orectolobiformes,Heterodontiformes,and Squaliformes） were clustered as another clade.The phylogenetic relationship is（（（Carcharhiniformes＋Lamniformes）＋Orectolobiformes） ＋Heterodontiformes）＋Squaliformes.The genetic variation analysis of main genes（13 protein coding genes and 2 ribosomal RNA genes） among cartilaginous fish species showed that nad5 and nad4 genes are ideal molecular markers and can be used as supplementary molecular markers to cox1 gene,which can be used to analyze the genetic diversity among different groups and provide more basis for rational use of its biological resources.