Data from: Genome-wide signature of local adaptation linked to variable CpG methylation in oak populations

It has long been known that adaptive evolution can occur through genetic mutations in DNA sequence, but it is unclear whether adaptive evolution can occur through analogous epigenetic mechanisms, such as through DNA methylation. If epigenetic variation contributes directly to evolution, species under threat of disease, invasive competition, climate change or other stresses would have greater stores of variation from which to draw. We looked for evidence of natural selection acting on variably methylated DNA sites using population genomic analysis across three climatologically distinct populations of valley oaks. We found patterns of genetic and epigenetic differentiations that indicate local adaptation is operating on large portions of the oak genome. While CHG methyl polymorphisms are not playing a significant role and would make poor targets for natural selection, our findings suggest that CpG methyl polymorphisms as a whole are involved in local adaptation, either directly or through linkage to regions under selection.

长期以来，学界已明确适应性进化可通过DNA序列的遗传突变实现，但适应性进化是否亦可通过类似的表观遗传机制（epigenetic mechanisms）发生，目前尚无定论。若表观遗传变异可直接推动进化进程，那么面临疾病、入侵性竞争、气候变化或其他胁迫威胁的物种，便可拥有更为充足的变异储备以供选择利用。本研究通过对三个气候特征迥异的山谷栎种群开展群体基因组分析，探寻自然选择作用于可变甲基化DNA位点的证据。我们发现遗传与表观遗传的分化模式表明，栎树基因组的大片区域正经历本地适应性演化。尽管CHG甲基化多态性未发挥显著作用，亦难以成为自然选择的有效靶标，但我们的研究结果表明，CpG甲基化多态性整体上可通过直接参与或与受选择区域连锁的方式，参与本地适应过程。