基于线粒体COⅠ的DNA条形码在对虾科种类鉴定中的研究

The research of COⅠ-based DNA barcoding in Penaeidaes’ identification

  • 摘要: 对虾科包含有26个属,约有200多种对虾,由于同属内的对虾在形态上非常相似,只呈现细微的差别,因此使得只基于形态学对对虾科物种的鉴别非常困难。为确定DNA条形码技术在对虾科物种鉴别的可行性,本研究中,采用线粒体细胞色素c氧化酶亚基Ⅰ(COⅠ)基因研究了32种对虾的核苷酸组成、对虾种间及种内遗传距离,用邻接法构建32种对虾COⅠ基因序列系统发生树。结果显示,对虾COⅠ基因组成偏倚明显,A+T含量(61.5%)显著高于G+C(38.5%)。基于Kimura双参数模型计算,32个物种的种内平均遗传距离为0.003,种间平均遗传距离(0.468)是种内遗传距离的156倍,符合Hebert提出的种间遗传距离大于或等于10倍种内遗传距离的标准。在系统进化树中,32种对虾中有30种对虾都以较高的置信度聚合成独立的分支。可见,线粒体COⅠ基因作为对虾科DNA条形码在物种的鉴别上具有很好的应用性,可以作为形态学分类系统的必要补充和佐证。

     

    Abstract: The Penaeidae comprises 26 genera and approximately 200 species as most of Penaeidae shrimps in the same genus are morphologically similar, and just exhibited subtle morphological differences, which makes identification of Penaeidae shrimps a difficult task based on taxonomic keys alone. In order to define the practicability of DNA barcoding in identification of Penaeidae shrimps, in this study, we used COⅠ gene to examine 32 kinds of Penaeidaes’ nucleotide composition, interspecific genetic distance and intraspeccific genetic distance, and to build neighbor-joining tree of 32 kinds of Penaeidae based on mtDNA COⅠ gene. As a result, the COⅠ sequences of 32 kinds of Penaeidae present base preference. On average, the content of A+T (61.50%)was significantly higher than that of G+C (38.50%). As calculated by Kimera-2-parameter model, the mean distance within-species was 0.003, the mean distance pairwise-species (0.468)is 156 times greater than the mean distance within-species. The phylogeny showed that 30 kinds of Penaeidae from 32 kinds of Penaeidae could converge upon a monophyly with high support values. We can see the good applicability of mitochondrial COⅠ-based DNA barcoding in Penaeidaes’ identification and use it as a necessary complement and a test of morphological taxonomic system.

     

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