长柄双花木种群遗传结构及种群历史

Population Genetic Structure and Demographic History of Disanthus cercidifolius var.longipes

【目的】分析长柄双花木种群遗传多样性和遗传结构,探讨其种群演化历史,加深对该物种进化过程的理解,为其遗传资源保护、开发利用提供理论基础。【方法】利用15对能获得高多态性扩增产物的SSR引物,采用TP-M13-SSR技术检测长柄双花木全分布区12个自然种群261株个体的遗传多态性,应用Gene Marker软件进行基因分型,FSTAT估算遗传参数,ARLEQUIN进行分子方差分析,STRUCTURE对所有个体进行Bayesian聚类分析,Bottleneck检测种群遗传瓶颈效应。【结果】15个SSR位点共检测到129个等位基因,平均每个位点上的等位基因数和有效等位基因数分别为8.6和3.5,观测杂合度和期望杂合度分别为0.37和0.67;种群水平上,平均每个位点上的等位基因数和有效等位基因数分别为3.4和2.1,观测杂合度和期望杂合度分别为0.35和0.43;私有基因丰富度和种群内近交系数分别为0.15和0.19。除道县种群外,其他种群极显著偏离Hardy-Weinberg平衡,表现出杂合子缺失。种群间遗传差异极显著(P<0.001)。12个种群可归类为2个类群,大多数个体谱系清晰。在近期的进化过程中,种群遗传结构稳定,未经历遗传瓶颈事件。【结论】长柄双花木在物种和种群水平上,维持较丰富的遗传变异,具有较高的进化潜力。近期生境碎片化和遗传漂移对长柄双花木种群遗传多样性影响较小。种群间的自然屏障、气候变迁和人类干扰导致的种群生境碎片化,是其现代地理分布格局和种群遗传结构的主要成因,这可为该物种遗传资源保护策略的制定提供科学依据。

【Objective】Population genetic diversity and genetic structure of Disanthus cercidifolius var.longipes were analyzed,and its population demographic history was speculated,so as to deepen understanding on its evolutionary process,and to provide a theoretical basis for conservation and utilization of its genetic resources.【Method】Genetic diversity of 261 individuals from 12 natural populations of the species were estimated at 15 polymorphic loci using TP-M13-SSR technology.All sampled individuals were genotyped using Gene Marker,genetic parameters were assessed with FSTAT,analysis of molecular variance was carried out with ARLEQUIN,Bayesian clustering analysis was conducted for all sampled individuals with STRUCTURE,and genetic bottleneck effect was detected by Bottleneck software.【Result】A total of 129 alleles were detected at 15 loci,and the mean allele number and effective allele number at each locus were 8.6 and 3.5,respectively.The mean observed heterozygosity and expected heterozygosity were 0.37,0.67.At population level,the mean allele number and effective allele number were 3.4 and 2.1,the mean observed heterozygosity and expected heterozygosity were 0.35 and 0.43,respectively.The private allelic richness and within-population inbreeding coefficient were 0.15 and 0.19,respectively.All populations deviated significantly from HWE with an excess of homozygotes except DX population.The genetic differentiation between populations was statistically significant(P<0.001).All the populations were classified into two clusters,and the lineages of most individual were clear.The populations had not experienced genetic bottleneck events over the historical evolutionary process.【Conclusion】Our results demonstrated that D.cercidifolius var.longipes maintained a moderate to high genetic variation,and the habitat fragmentation and genetic drift has not yet declined within-population genetic diversity.This species has high evolutionary potential.The geographic isolation,habitat fragmentation caused by climate change and human disturbance might be the main causes for the formation of current geographical distribution pattern and population genetic structure.Overall,our study provides scientific evidences for making effective conservation strategies for the species.