Epigenetic inheritance has been proposed to contribute to adaptation and acclimation via two information channels: (i) inducible epigenetic marks that enable transgenerational plasticity and (ii) noninducible epigenetic marks resulting from random epimutations shaped by selection. We studied both postulated channels by sequencing methylomes and genomes of Baltic three-spined sticklebacks (Gasterosteus aculeatus) along a salinity cline. Wild populations differing in salinity tolerance revealed differential methylation (pop-DMS) at genes enriched for osmoregulatory processes. A two-generation experiment demonstrated that 62% of these pop-DMS were noninducible by salinity manipulation, suggesting that they are the result of either direct selection or associated genomic divergence at cis- or trans-regulatory sites. Two-thirds of the remaining inducible pop-DMS increased in similarity to patterns detected in wild populations from corresponding salinities. The level of similarity accentuated over consecutive generations, indicating a mechanism of transgenerational plasticity. While we can attribute natural DNA methylation patterns to the two information channels, their interplay with genomic variation in salinity adaptation is still unresolved.

已提出表观遗传通过两个信息通道为适应和适应做出贡献：（i）诱导型表观遗传标记，可实现跨代可塑性，以及（ii）非选择性表观遗传标记，这些标记是由于选择形成的随机表观突变而产生的。我们通过对波罗的海三棘棘背（（Gasterosteus aculeatus）沿盐度线。耐盐性不同的野生种群在渗透调节过程富集的基因上显示差异甲基化（pop-DMS）。一项两代实验表明，盐度操作无法诱导这些pop-DMS中的62％，这表明它们是直接选择或相关基因组在顺式或反式调控位点处分化的结果。其余三分之二的可诱导pop-DMS的增加与从相应盐度在野生种群中检测到的模式相似。相似的水平在连续的世代中更加突出，表明了跨代可塑性的机制。虽然我们可以将天然的DNA甲基化模式归因于两个信息通道，但它们与盐度适应性的基因组变异之间的相互作用仍未解决。