论文部分内容阅读
本研究选用DNA条形码的通用基因片段,采用特异性扩增测序及与GenBank已有序列结合分析的方法,进行了鲻科(Mugilidae)6属17种鱼类的COI基因片段的序列比较、分子树构建和系统进化研究。研究表明,在所得的17种鲻科鱼类共有的555bp COI基因片段中平均GC含量为46.9%。其中,第二密码子位点含量最高(49.8%~56.2%),平均54.9%;第一密码子变化范围最大(31.9%~48.6%),平均42.9%;第三密码子差别不显著(42.5%~43.4%),平均42.7%。依据Kimura-2-parameter模型(K2P),17种鲻科鱼类种内遗传距离的平均值为0.004 5,种间遗传距离为0.191,是种内遗传距离的42倍。在分子系统树上,所有物种均呈单系,5属为独立分支,只有隶属于梭属(Liza)的尖头梭(Liza tade)与莫鲻属(Moolgarda)聚类,表现出与传统形态学分类不一致的结果。本研究结果验证了线粒体COI基因作为DNA条形码对鲻科鱼类进行物种鉴定的有效性,可用于辅助探讨鲻科科下属、种分类阶元系统发育问题。
In this study, we selected the common DNA fragments of DNA barcodes and sequenced the COI gene fragments of 17 species of 6 genera of Mugilidae by using specific amplification and sequencing combined with existing sequences in GenBank. Construction and evolution of the system. The results showed that the average content of GC in the 555 bp COI gene fragment shared by the 17 species of saims was 46.9%. Among them, the content of the second codon site was the highest (49.8% -56.2%), with an average of 54.9%; the first codon was the largest (31.9% -48.6%) with an average of 42.9%; the third codon was not significantly different % ~ 43.4%), with an average of 42.7%. According to the Kimura-2-parameter model (K2P), the average genetic distance among 17 species of clams was 0.004 5, the inter-species genetic distance was 0.191, which was 42 times of the intra-species genetic distance. In the molecular phylogenetic tree, all species are monophyletic, and five are independent branches. Only Liza tade and Moolgarda belong to Liza, Unequal results. The results of this study validate the effectiveness of mitochondrial COI gene as a DNA barcode for identification of species in the family Gryllidae, and can be used to assist in the development of taxonomic and phylogenetic relationships of the subfamilies and species.