基于线粒体Cytb序列的3个宽体金线蛭群体遗传多样性分析

对江苏省扬州高邮、苏州张家港、泰州海陵3个地区宽体金线蛭自然群体的线粒体Cytb基因全序列进行了测定和分析。结果显示:宽体金线蛭Cytb基因全长1 146 bp,样本的A、G、T、C平均含量分别为27.57%、15.77%、43.49%、13.17%,A+T含量(71.06%)明显高于G+C含量(28.94%)。在77个宽体金线蛭样本中,共检测到96个多态位点,其中有58个简约信息位点,获得47个单倍型,共享单倍型数目1个。3个宽体金线蛭群体的平均单倍型多样性、核苷酸多样性、平均核苷酸差异数分别为0.9781、0.0133、15.20,其中泰州海陵群体的单倍型多样度(0.987 7)和核苷酸多样度(0.013 1)最高。3个群体间的遗传分化指数F_(st)为0.065 1～0.175 6,且差异显著(P0.05),不同群体间存在一定的遗传分化。分子方差分析(AMOVA)表明,11.13%的变异来自群体间,88.87%的变异来自群体内。用邻接法构建的单倍型系统发育进化树显示,不同地理群体的个体呈交错分布,没有形成明显的地理谱系。中性检验和核酸不配对分布结果表明,3个宽体金线蛭野生群体总体大小保持相对稳定,没有发生明显的种群扩张。

Genetic diversity analysis of three populations of Whitmania pigra Whitman based on mitochondrial Cytb gene

The mitochondrial Cytb genes were sequenced and analyzed of W. pigra Whitman from three wild geographical populations including Gaoyou Yangzhou, Zhangjiagang Suzhou and Hailing Taizhou. The results showed that Cytb sequence of W. pigra was 1 146 bp, and the average contents of A, G, T and C were 27.57%, 15.77%, 43.49% and 13.17%, respectively. The A+T content (71.06%) was higher than that of G+C(28.94%).Among examined 77 individuals, 96 polymorphic sites and 58 parsimony information sites were detected. Besides,47 haplotypes were found and there was only one shared haplotype. The total haplotype diversity, nucleotide diversity, and the average nucleotide difference were 0.978 1, 0.013 3, and 15.20, respectively. The Hailing Taizhou population has the highest haplotype diversity (0.987 7) and nucleotide diversity (0.013 1). The genetic differentiation index F_st of the three populations ranged from 0.065 1 to 0.175 6, and the difference was significant (P<0.05), which indicated that there was a certain genetic differentiation among different populations. The analysis result of molecular variance (AMOVA) showed a higher percentage of 88.87% within-population variation than that of 11.13% among-population variation. The haplotype neighbor-joining (NJ) tree with individuals of different geographical groups radiated showed no phylogeographic structure among three populations. Neutral test and mismatch distribution analysis revealed that the overall size of the three populations of W. pigra remained relatively stable, with no significant population expansion.