基于SNP标记的青海湖裸鲤遗传多样性及种群结构研究

Genetic diversity and population structure of Gymnocypris przewalskii based on SNP markers

  • 摘要: 为探究青海湖裸鲤 (Gymnocypris przewalskii) 的种质资源现状,为该物种保护措施的制定提供参考依据。首次利用基因分型技术 (Genotyping-by-sequencing, GBS),对青海湖水域的6个地理群体共72尾青海湖裸鲤进行单核苷酸多态性 (Single nucleotide polymorphism, SNP) 标记开发和遗传特征分析。共检测出1 600 061个SNP位点,质控后筛选出45 266个高质量的SNP位点用于遗传分析,发现核苷酸多样性 (Pi) 为0.317 0~0.327 4,观测杂合度 (Ho) 和期望杂合度 (He) 分别为0.459 4~0.482 3和0.336 7~0.344 4。6个地理群体的遗传距离 (D) 为0.018 4~0.023 3,两两群体的遗传分化系数 (Fst) 均不显著 (P>0.05)。分子方差分析 (Analysis of molecular variances, AMOVA) 显示102.37%的遗传变异来自群体内;群体遗传结构和系统发育进化树分析均显示6个群体属于一个集群,具有遗传同质性;而主成分判别分析 (Discriminant analysis of principal components, DAPC) 表明哈尔盖河、黑马河和沙柳河群体相互交叉聚类,其余3个地理群体分别聚类。综上,6个青海湖裸鲤群体的Ho均大于He,种群结构单一。

     

    Abstract: To investigate the genetic diversity and genetic differentiation of natural resources of Gymnocypris przewalskii, and provide references for its conservation measures, we collected 72 individuals of G. przewalskii from six natural populations in Qinghai Lake to analyze the genomic SNP and genetic characteristics by using simplified genome sequencing. Altogether 1 600 061SNP markers were obtained, and 45 266 high-quality SNP loci were screened for genetic analysis after filtering. The average Pi diversity index was 0.317 0–0.327 4. The average observed heterozygosity (Ho) and expected heterozygosity (He) were 0.459 4–0.482 3 and 0.336 7–0.344 4, respectively. The genetic distance (D) was 0.018 4–0.023 3 and the genetic differentiation index (Fst) were not significant (P>0.05). AMOVA analysis shows that the genetic variation was 102.37% within populations. Further-more, both population structure and phylogenetic tree analysis show that the six G. przewalskii populations clustered into one glade with similar genetic structure. In contrast, the genetic structure obtained from DAPC analysis was relatively clearer, showing that the Haergai, Heima and Shaliu River populations cross-clustered with each other, while the remaining three populations clustered into three other branches. In conclusion, the observed heterozygosity of the six geographic populations was higher than the expected value, with a homogeneous population structure.

     

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