Epigenetic variation might play an important role in generating adaptive phenotypes by underpinning within-generation developmental plasticity, persistent parental effects of the environment (e.g., transgenerational plasticity), or heritable epigenetically based polymorphism. These adaptive mechanisms should be most critical in organisms where genetic sources of variation are limited. Using a clonally reproducing freshwater snail (Potamopyrgus antipodarum), we examined the stability of an adaptive phenotype (shell shape) and of DNA methylation between generations. First, we raised three generations of snails adapted to river currents in the lab without current. We showed that habitat-specific adaptive shell shape was relatively stable across three generations but shifted slightly over generations two and three toward a no-current lake phenotype. We also showed that DNA methylation specific to high-current environments was stable across one generation. This study provides the first evidence of stability of DNA methylation patterns across one generation in an asexual animal. Together, our observations are consistent with the hypothesis that adaptive shell shape variation is at least in part determined by transgenerational plasticity, and that DNA methylation provides a potential mechanism for stability of shell shape across one generation.

中文翻译：

---

克隆蜗牛的世代表型和表观遗传稳定性。

表观遗传变异可能通过支持代内发育可塑性，环境的持续父母效应（例如，跨代可塑性）或可遗传的基于表观遗传的多态性，在产生适应性表型中发挥重要作用。这些适应性机制在变异的遗传来源受到限制的生物中应该是最关键的。使用无性繁殖的淡水蜗牛（Potamopyrgus antipodarum），我们研究了适应性表型（壳形）的稳定性以及各代之间DNA甲基化的稳定性。首先，我们在实验室中饲养了三代适应河流的蜗牛，而没有电流。我们表明，特定于生境的适应性壳形在三代中相对稳定，但在第二代和第三代中向无当前湖表型的方向略有偏移。我们还表明，特定于大电流环境的DNA甲基化在一代人时间内是稳定的。这项研究提供了无性动物中一代人的DNA甲基化模式稳定性的第一个证据。综上所述，我们的观察结果与以下假设相吻合：自适应壳的形状变化至少部分取决于跨代可塑性，