Data from: Variation in DNA methylation transmissibility, genetic heterogeneity and fecundity-related traits in natural populations of the perennial herb Helleborus foetidus

Inferences about the role of epigenetics in plant ecology and evolution are mostly based on studies of cultivated or model plants conducted in artificial environments. Insights from natural populations, however, are essential to evaluate the possible consequences of epigenetic processes in biologically realistic scenarios with genetically and phenotypically heterogeneous populations. Here we explore associations across individuals between DNA methylation transmissibility (proportion of methylation-sensitive loci whose methylation status persists unchanged after male gametogenesis), genetic characteristics (assessed with AFLP markers), seed size variability (within-plant seed mass variance), and realized maternal fecundity (number of recently recruited seedlings), in three populations of the perennial herb Helleborus foetidus along a natural ecological gradient in southeastern Spain. Plants (sporophytes) differed in the fidelity with which DNA methylation was transmitted to descendant pollen (gametophytes). This variation in methylation transmissibility was associated with genetic differences. Four AFLP loci were significantly associated with transmissibility and accounted collectively for about 40% of its sample-wide variance. Within-plant variance in seed mass was inversely related to individual transmissibility. Number of seedlings recruited by individual plants was significantly associated with transmissibility. The sign of the relationship varied between populations, which points to environment-specific, divergent phenotypic selection on epigenetic transmissibility. Results support the view that epigenetic transmissibility is itself a phenotypic trait whose evolution may be driven by natural selection, and suggest that in natural populations epigenetic and genetic variation are two intertwined, rather than independent, evolutionary factors.

有关表观遗传学（epigenetics）在植物生态学与进化中所发挥作用的相关推论，大多源自人工环境下针对栽培植物或模式植物开展的研究。然而，若要在兼具遗传与表型异质性的种群所构成的生物学真实场景中，评估表观遗传过程可能产生的影响，来自自然种群的研究证据则不可或缺。本研究以西班牙东南部沿自然生态梯度分布的3个多年生草本臭嚏根草（Helleborus foetidus）种群为研究对象，探究了个体间DNA甲基化传递率（即雄配子发生（male gametogenesis）后甲基化状态保持不变的甲基化敏感位点（methylation-sensitive loci）占比）、遗传特征（通过扩增片段长度多态性（AFLP）标记进行评估）、种子大小变异（植株内种子质量方差）与实际母本繁殖力（新近定植幼苗的数量）之间的关联。植株（孢子体（sporophytes））在DNA甲基化向子代花粉（配子体（gametophytes））传递的保真度上存在个体差异。这种甲基化传递率的变异与遗传差异显著相关。共有4个AFLP位点与甲基化传递率显著相关，其共同解释了样本整体约40%的传递率变异。植株内种子质量方差与个体甲基化传递率呈负相关关系。植株的定植幼苗数量与甲基化传递率显著相关，且该关联的方向在不同种群间存在差异，这表明表观遗传传递率受到环境特异性的分化表型选择（phenotypic selection）作用。本研究结果支持"表观遗传传递率本身就是一种可受自然选择驱动其进化的表型性状"这一观点，并表明在自然种群中，表观遗传变异与遗传变异是两个相互交织而非独立的进化因子。