基于COⅡ基因序列的中国近海12种蛸亚科动物的分子系统进化研究

Phylogenic study of Octopodinae in the China Seas based on COⅡ partial sequences

关键词:  蛸亚科  CoⅡ  基因分子系统进化

Key words:  Octopodinae  CoⅡ  Molecular phylogenetic analysis

摘要:

为探讨我国近海蛸亚科(Octopodinae)动物的系统进化关系，本研究通过PCR扩增得到了东海区蛸亚科2属12种蛸类的线粒体COⅡ基因部分序列。纯化后测序，利用多个生物软件对序列变异和碱基组成进行分析。Kimura双参数法计算遗传距离，并结合GenBank上相关头足类同源序列构建NJ、UPGMA系统树。结果表明，蛸类COⅡ基因符合一般线粒体基因A+T含量较高的特点，有较为明显的反G偏倚。其变异位点较多的集中在第三位，编码的氨基酸序列变异位点较少。遗传距离分析表明，所得物种的遗传距离介于0.000与0.232 3之间，且大多位于0.140 0~0.200 0之间。聚类分析表明，所研究蛸类被明显地聚为两大类，即以真蛸为代表的长腕类和以砂蛸为代表的短腕类，证明了蛸属的非单系性。探讨了部分蛸类的分类地位，并就COⅡ基因在头足类系统进化研究的应用潜力进行了剖析。

Abstract:

Partial sequences of mitochondrial COⅡ gene in 12 octopus species in 2 genus of Octopodinae, were amplified and sequenced to investigate the phylogenesis of Octopodinae in China coastal waters. Multiple biological softwares were employed to analyze the sequence variations and nucleotide composition. Genetic distances were calculated by Kimura-2-parameter method and phylogenetic trees were constructed by both NJ and UPGMA method with more cephalopoda sequences available in GenBank. Results showed that COⅡ genes of octopus were rich in A and T nucleotide bases, as most other mitochondrial genes represent. The sequences showed an obvious anti-G bias. The most variable sites among species lay in the last site of codon of the coding region, leading to less amino acid variation. Genetic distances calculated between species were 0.000 0~0.232 3, and most of them were between 0.140 0 and 0.200 0. The constructed phylogenetic tree suggested that the 12 Octopus species were from two groups: long-arm group represented by Octopus vulgaris and short-arm group represented by O. aegina, which again supported the non-monophyletic of Octopus genus. The Octopus genus can be divided into two or more distant genus according to this study. The taxonomic position of some Octopodinae species was also discussed, and the potential application of COⅡ gene in cephalopoda classification and phyletic evolution was suggested. The results of this study may help understanding the taxonomy and phyletic evolution of Octopodinae species in China coastal waters and contribute to better exploitation and farming of these precious species.