Data from: Genetic diversity and multiple origins of polyploid Atriplex nummularia Lindl. (Chenopodiaceae).

Few studies have described the genetic diversity within and between populations of polyploid plant species despite the general acceptance of the importance of polyploidy in plant diversification and speciation. The genus Atriplex has a complex evolutionary history in Australia that has included polyploidy and hybridization among perennial forms. The octoploid, dioecious species Atriplex nummularia is proposed to have evolved from an octoploid ancestor in the coastal semi-arid fringe of south-western Australia, and to have spread east and diversified into taxa which occupy edaphically different habitats. Despite interest in the diversification of the genus, and the ecological and economic importance of A. nummularia, there are no descriptions of the genetic structure of the species. Nuclear microsatellite markers and principal coordinate analysis, analysis of molecular variance, Bayesian and phenetic analyses were used to investigate the diversity and taxonomic relationships of two common subspecies of A. nummularia. Genetic diversity was high overall (A = 509, A′ = 42.4, Ho = 0.824, H′ = 2.8), but values were significantly lower in the western subspecies, A. nummularia ssp. spathulata. As in other outbreeding, perennial species, most of the genetic diversity was within populations (FST = 0.125). Clear divergence of subspecies was evident in principal coordinate analysis, neighbor-joining and Bayesian clustering analyses and the differentiation of populations was very low within subspecies (FSC = 0.048). These findings support the taxonomic separation of the two subspecies. Clustering patterns based on Bayesian analyses suggested that the polyploid subspecies of A. nummularia have multiple origins.

尽管学界已普遍认同多倍化在植物类群分化与物种形成过程中的关键作用，但针对多倍体植物物种的种群内及种群间遗传多样性的相关研究仍相对稀缺。滨藜属（Atriplex）在澳大利亚的演化历史极为复杂，涉及多年生类群间的多倍化与杂交事件。八倍体雌雄异株物种滨藜（Atriplex nummularia）被认为起源于澳大利亚西南部沿海半干旱边缘地带的八倍体祖先类群，随后向东扩散并分化为适应不同土壤生境的类群。尽管学界对滨藜属的类群分化以及滨藜（Atriplex nummularia）的生态与经济价值已有诸多关注，但目前仍未有关于该物种种群遗传结构的相关研究报道。本研究采用核微卫星标记（nuclear microsatellite markers）结合主坐标分析（principal coordinate analysis）、分子方差分析（analysis of molecular variance）、贝叶斯聚类分析与表型分析，对滨藜（Atriplex nummularia）的两个常见亚种的遗传多样性与分类学关系展开探究。整体而言，该物种的遗传多样性水平较高（等位基因数A=509、标准化等位基因丰富度A'=42.4、观测杂合度Ho=0.824、香农多样性指数H'=2.8），但西部亚种匙叶滨藜（Atriplex nummularia ssp. spathulata）的遗传多样性水平显著更低。与其他异交多年生植物物种一致，该物种的大部分遗传变异分布于种群内部（种群间遗传分化系数FST=0.125）。主坐标分析、邻接法（neighbor-joining）分析与贝叶斯聚类分析均显示两个亚种存在显著的遗传分化，且亚种内的种群间遗传分化水平极低（亚种种内遗传分化系数FSC=0.048）。上述研究结果支持将该物种的两个亚种划分为独立分类单元的分类学处理。基于贝叶斯分析得到的聚类模式表明，滨藜（Atriplex nummularia）的多倍体亚种存在多次独立起源事件。