Epigenetic change is considered relatively unstable and short‐lived, raising questions of its contribution to long‐term adaptive potential. However, epigenetic modifications can accumulate in the presence of environmental stress, resulting in beneficial epigenetic memories where environments are challenging. Diverging epigenetic memories have been observed across large spatial scales, and can persist through multiple generations. It is unknown, however, to what extent epigenetic variation contributes to fine‐scale population structure and evolution. We compared DNA methylation patterns between a steep, altitudinal gradient (<2 km) and a wide spatial gradient (>500 km) using whole genome bisulphite sequencing data from 30 Fragaria vesca plants germinated and grown in controlled conditions. To assess the stability of spatial epigenetic variation in the presence of an environmental stressor, we applied acute drought stress to part of the plants and quantified drought‐induced changes in DNA methylation signatures. We find that epigenetic memories and genomic islands of epigenetic divergence arise even at fine spatial scale, and that distinct spatial scales are featured by distinct epigenetic patterns. For example, demethylation of transposable elements consistently occurred at the large but not the fine spatial scale, while methylation differentiation for most biological processes were shared between spatial scales. Acute drought stress did not result in significant epigenetic differentiation. Our results indicate that population history, rather than short‐term environmental stress, plays a dominant role in shaping epigenetic signatures. Specifically, repeated historical stress levels associated with heterogeneous environmental conditions may be required for acquiring a stable epigenetic memory and for coping with future environmental change.

中文翻译：

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不同空间尺度下野草莓DNA甲基化模式的生态差异

表观遗传学的变化被认为是相对不稳定和短暂的，这引发了人们对其长期适应潜力的贡献的疑问。但是，表观遗传修饰会在环境压力下累积，从而在环境具有挑战性的情况下产生有益的表观遗传记忆。在较大的空间尺度上观察到了不同的表观遗传记忆，并且可以持续多代。然而，尚不清楚表观遗传变异在多大程度上有助于精细的种群结构和进化。我们使用来自30种草莓的全基因组亚硫酸氢盐测序数据比较了陡峭的海拔梯度（<2 km）和宽的空间梯度（> 500 km）之间的DNA甲基化模式植物在受控条件下发芽和生长。为了评估在环境胁迫条件下空间表观遗传变异的稳定性，我们将急性干旱胁迫应用于部分植物，并量化了干旱诱导的DNA甲基化标记变化。我们发现表观遗传的记忆和表观遗传差异的基因组岛即使在精细的空间尺度上也会出现，并且不同的空间尺度以不同的表观遗传模式为特征。例如，转座因子的去甲基化始终在较大的空间尺度上发生，而不是在精细的空间尺度上发生，而大多数生物学过程的甲基化分化在空间尺度之间共享。急性干旱胁迫并未导致显着的表观遗传分化。我们的结果表明，人口历史而非短期环境压力 在塑造表观遗传特征中起主导作用。具体而言，可能需要与异质环境条件相关的重复历史压力水平，以获得稳定的表观遗传记忆并应对未来的环境变化。