Leung Christelle, Angers Bernard, Bergeron Patrick
Department of Biological Sciences, Bishop's University, Sherbrooke, QC, J1M 1Z7, Canada.
Department of Biological Sciences, Université de Montréal, Montréal, QC, H3C 3J7, Canada.
Environ Epigenet. 2020 Jan 30;6(1):dvz026. doi: 10.1093/eep/dvz026. eCollection 2020 Jan.
Physiological changes in anticipation of cyclic environmental events are common for the persistence of populations in fluctuating environments (e.g. seasons). However, dealing with sporadic resources such as the intermittent production of seed masting trees may be challenging unless reliable cues also make them predictable. To be adaptive, the anticipation of such episodic events would have to trigger the corresponding physiological response. Epigenetic modifications could result in such physiological anticipatory responses to future changes. The eastern chipmunk () is known to adjust its reproductive activity to match juvenile weaning with peak seed availability of masting trees, which are essential for their survival. We therefore expected that epigenetic changes would be linked to spring reproductive initiation in anticipation for beech seed availability in fall. We correlated the variation of DNA methylation profiles of 114 adult chipmunks captured in May with beech seeds abundance in September, over 4 years, for three distinct populations, as well as individuals sampled twice during reproductive and non-reproductive years. The significant correlation between spring epigenetic variation and the amount of food in the fall confirmed the phenotypic flexibility of individuals according to environmental fluctuations. Altogether, these results underlined the key role of epigenetic processes in anticipatory responses enabling organisms to persist in fluctuating environments.
对于处于波动环境（如季节变化）中的种群而言，预期周期性环境事件时出现的生理变化很常见。然而，应对诸如种子大年树木间歇性产种这类零星资源可能具有挑战性，除非可靠的线索也能使这些资源具有可预测性。为了具有适应性，对这类偶发事件的预期必须触发相应的生理反应。表观遗传修饰可能会导致对未来变化产生这种生理预期反应。已知东部花栗鼠会调整其繁殖活动，以使幼崽断奶时间与种子大年树木的种子供应高峰期相匹配，而这些种子对它们的生存至关重要。因此，我们预计表观遗传变化会与春季繁殖开始相关联，以便预期秋季山毛榉种子的可获得性。在4年时间里，我们将5月份捕获的114只成年花栗鼠的DNA甲基化谱变化与9月份的山毛榉种子丰度进行了关联分析，涉及三个不同种群，以及在繁殖年和非繁殖年两次采样的个体。春季表观遗传变化与秋季食物量之间的显著相关性证实了个体根据环境波动所具有的表型灵活性。总之，这些结果强调了表观遗传过程在预期反应中的关键作用，使生物体能够在波动环境中持续生存。
