应用细胞色素b序列对鲷科鱼类进行种类鉴定的可行性研究

Identification standard of Sparid species based on cytochrome b sequences

  • 摘要: 从NCBI分子生物学数据库下载鲷科鱼类10属12种共24条Cyt b序列,通过序列比对最终获得1 070 bp的共有序列。其中,共检测到675个单态位点,393个变异位点,2个未知位点,没有检测到插入缺失。每个种具有的种特征性位点数为4到24个不等,平均约为12.42个。种间遗传距离分布范围为0.105±0.010(SE)到0.220±0.017(SE),均值为0.180±0.0231(SD),而种内遗传距离要小于或等于0.018±0.004(SE),均值为0.007±0.006(SD),因此,种间遗传距离要远远大于种内遗传距离。系统发育分析发现,来源于同一种内的2条序列都被聚为一个类群。以上分析显示不同鲷科种类能够通过Cyt b序列较好的进行区分,据此提出,当2个鲷科鱼类个体基于以上Cyt b序列计算得到的遗传距离如小于0.018时可以初步判断属于同一种,大于0.105则为不同种。研究为鲷科鱼类的分子种类鉴定提供了部分基础资料。

     

    Abstract: Twenty-four Sparid cytochrome (Cyt) b sequences belonging to 10 genus, 12 species were downloaded from the molecular biology database NCBI. Of the 1 070 bp consensus sequences obtained by alignment, 675 sites were monophic, 393 were variable sites, 2 were missing sites, and in which no gap was detected. The species-specific sites ranged from 4 to 24 with an average of 12.42 for each species. The distribution range for the interspecies genetic distances was from 0.105 0.010(SE) to 0.220 0.017(SE), and the mean value for that was 0.180±0.0231(SD), whereas all of the intraspecies genetic distances were equal to or less than 0.018±0.004(SE), and the mean value was 0.007±0.006(SD).The genetic distances between species therefore were far more than those within species. Furthermore, phylogenetic analysis also indicated that all the sequences from the same species were clustered to one group. Such result suggested that the Sparid species could be distinguished clearly using Cyt b sequences. Based on this examination of the reference sequences, we provisionally suggested that the genetic distance less than 0.018 between 2 Sparid individuals indicates positive species identification, whereas more than 0.105 indicates negative species identification. This study provides some guidelines for the molecular species identification of the Sparidae.

     

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