Department of Ecology & Evolutionary Biology, Cornell University, Ithaca, New York.
Lab of Ornithology, Cornell University, Ithaca, New York.
Mol Ecol. 2019 Aug;28(16):3722-3737. doi: 10.1111/mec.15186. Epub 2019 Aug 11.
Individuals often differ in their ability to cope with challenging environmental and social conditions. Evidence from model systems suggests that patterns of DNA methylation are associated with variation in coping ability. These associations could arise directly if methylation plays a role in controlling the physiological response to stressors by, among other things, regulating the release of glucocorticoids in response to challenges. Alternatively, the association could arise indirectly if methylation and resilience have a common cause, such as early-life conditions. In either case, methylation might act as a biomarker for coping ability. At present, however, relatively little is known about whether variation in methylation is associated with organismal performance and resilience under natural conditions. We studied genome-wide patterns of DNA methylation in free-living female tree swallows (Tachycineta bicolor) using methylated DNA immunoprecipitation (MeDIP) and a tree swallow genome that was assembled for this study. We identified areas of the genome that were differentially methylated with respect to social signal expression (breast brightness) and physiological traits (ability to terminate the glucocorticoid stress response through negative feedback). We also asked whether methylation predicted resilience to a subsequent experimentally imposed challenge. Individuals with brighter breast plumage and higher stress resilience had lower methylation at differentially methylated regions across the genome. Thus, widespread differences in methylation predicted both social signal expression and the response to future challenges under natural conditions. These results have implications for predicting individual differences in resilience, and for understanding the mechanistic basis of resilience and its environmental and social mediators.
个体在应对具有挑战性的环境和社会条件的能力方面常常存在差异。来自模型系统的证据表明，DNA 甲基化模式与应对能力的变化有关。如果甲基化通过调节糖皮质激素对挑战的释放等方式在控制对压力源的生理反应中发挥作用，那么这些关联可能是直接产生的。或者，如果甲基化和适应能力有共同的原因，如生命早期的条件，那么这种关联可能是间接产生的。在这两种情况下，甲基化都可能成为应对能力的生物标志物。然而，目前关于甲基化变异是否与自然条件下的个体表现和适应能力有关，还知之甚少。我们使用甲基化 DNA 免疫沉淀（MeDIP）和为此研究组装的树燕基因组，研究了自由生活的雌性树燕（Tachycineta bicolor）的全基因组 DNA 甲基化模式。我们确定了与社会信号表达（乳房亮度）和生理特征（通过负反馈终止糖皮质激素应激反应的能力）有关的基因组区域的差异甲基化。我们还询问了甲基化是否可以预测对随后的实验性挑战的适应能力。乳房羽毛较亮且应激适应能力较高的个体，其基因组上差异甲基化区域的甲基化程度较低。因此，广泛的甲基化差异预测了自然条件下社会信号表达和对未来挑战的反应。这些结果对预测适应能力的个体差异以及理解适应能力的机制基础及其环境和社会调节因素具有重要意义。
