基于16S rRNA 和Cyt b 基因序列探讨2 种梅童鱼的遗传分化

Discussion of relationship between Collichthys lucidus and C.niveatus based on 16S rRNA and Cyt b gene sequences

  • 摘要: 比较分析了棘头梅童鱼(Collichthys lucidus)和黑鳃梅童鱼(C.niveatus)的16S rRNA和Cyt b基因片段序列差异及遗传分化程度。在长度为526 bp的16S rRNA和379 bp的Cyt b基因片段的核苷酸序列中,2种间共检测到44处核苷酸替代。分析结果表明,2个基因片段的鸟嘌呤(G)含量较低,在Cyt b蛋白质编码基因第三密码子位点上表现尤为明显。基于16S rRNA和Cyt b基因片段分析结果显示,2种间平均遗传距离分别为0.012和0.111。构建的系统树显示2种梅童鱼在这2个基因片段上存在显著的遗传分化。根据Cyt b基因2%/百万年的进化速率推断,棘头梅童鱼与黑鳃梅童鱼的分化时间约为550万年,发生于上新世(Pliocene)早期。

     

    Abstract: Collichthys lucidus and C.niveatus are commercially important fishery resources in China. Partial nucleotide sequences of mitochondrial DNA 16S rRNA and Cyt b gene fragments were sequenced and analyzed to study the relationship between C.lucidus and C.niveatus. Forty-four nucleotide substitutions were detected among 16S rRNA (526 bp) and Cyt b (379 bp) fragments. Nucleotide composition analysis indicated that the content of guanine (G) was relatively low in the two fragments, especially at the third codon position of Cyt b genes. Average genetic distances based on 16S rRNA and Cyt b between C.lucidus and C.niveatus were 0.012 and 0.111, respectively. The phylogenetic tree showedthat there was significant genetic divergence between C.lucidus and C.niveatus. According to the evolutionary rate of 2% perone million years, the estimated divergence time between C.lucidus and C.niveatus was 5.5 million years, which indicated an early Pliocene divergence for them.

     

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