Endocrine, genetic and epigenetic mechanisms of coping with environmental change in tropical birds

生物体如何应对环境中的不确定性？了解生物体如何在生理上应对自然变化的环境，对于预测包括人类在内的生物体对日益不可预测的环境的反应将是重要的，这些环境的特征是频繁的极端天气事件，如干旱和洪水。由于应对机制本身，即短期的生理和行为反应，在较长的时间内对环境变化做出反应，因此需要采取比较的方法来充分了解生物体在历史上如何对气候不确定性做出反应。为了确定脊椎动物如何在生理和分子水平上适应和应对环境变化，这项研究将同时探索作为肯尼亚生态梯度应激反应和整个基因组基础的鸟类基因的遗传和表观遗传变异模式，然后将这种变异与自然变化和实验控制的气候中的基因表达模式联系起来。这项研究将在实地和实验室培训高中生、本科生和研究生，特别是那些来自代表性不足群体的学生。培训将强调尖端的、可跨学科转移的综合工具。研究人员将与肯尼亚一个草根保护组织密切合作，通过一系列教学单元和公众陈述对农村学童进行保护和野生动物方面的教育。最后，研究人员将在纽约市各地和针对不同受众的热门文章中展示他们的工作结果。脊椎动物在生理上应对环境变化的主要方式之一是通过改变下丘脑-垂体-肾上腺(HPA)轴，这是控制压力反应的神经内分泌系统。HPA轴包括一系列激素、受体和其他分子，每种分子都可能对不同类型和不同时间尺度的环境变化做出反应。尽管了解HPA轴对环境变化的反应对于确定生物体如何应对环境的不确定性很重要，因为这是脊椎动物对环境应激源做出反应的首要方式之一，但许多其他的生理、内分泌和分子途径也受到环境应激源的影响。因此，为了理解动物如何适应和应对环境的不确定性，有必要采用一种全基因组的方法，将分子机制和更广泛的适应性遗传和表观遗传变异与生理功能联系起来。这项研究的目的是确定环境变化如何影响自适应遗传(DNA序列)和表观遗传变异(DNA甲基化)、基因功能(mRNA表达)和生理反应(激素活性)，以塑造自由生活的超级八哥种群的特定表型。这些种群是在撒哈拉以南非洲的一个大范围生态梯度上采样的，该梯度包括世界上一些最不可预测的气候带。基于非洲八哥的长期数据，并利用肯尼亚沿生态梯度建立的一系列新种群，这项工作将使研究人员能够开始了解环境诱导的选择压力如何塑造脊椎动物用来应对环境不确定性的分子机制、适应性进化反应和应对策略。

How do organisms cope with uncertainty in their environment? Understanding how organisms cope physiologically with naturally variable environments will be important for predicting organismal responses, including those in humans, to increasingly unpredictable environments characterized by frequent extreme weather events like droughts and floods. And since coping mechanisms themselves, short-term physiological and behavioral responses, respond to environmental variation over longer time periods, a comparative approach is needed to fully understand how organisms have historically responded to climatic uncertainty. To determine how vertebrates adapt to and cope with environmental variation at the physiological and molecular level, this study will simultaneously explore patterns of genetic and epigenetic variation in genes of birds that underlie the stress response and the entire genome across an ecological gradient in Kenya, and then relate this variation to patterns of gene expression in naturally variable and experimentally-controlled climates. This study will train high school students, undergraduates, and graduate students, particularly those from underrepresented groups, in the field and lab. Training will emphasize cutting-edge, integrative tools that are transferable across disciplines. Researchers will work closely with a grassroots Kenyan conservation organization to educate rural schoolchildren on conservation and wildlife through a series of teaching modules and public representations. Finally, researchers will present the results of their work locally around New York City and in popular articles aimed at a diverse audience.One of the primary ways that vertebrates cope physiologically with environmental variability is through changes in the hypothalamo-pituitary-adrenal (HPA) axis, the neuroendocrine system that controls reactions to stress. The HPA axis encompasses a cascade of hormones, receptors, and other molecules, each of which may respond to different types and timescales of environmental variation. Although understanding how the HPA axis responds to environmental variability is important for determining how organisms will cope with environmental uncertainty because it is one of the first ways that vertebrates respond to environmental stressors, many other physiological, endocrine, and molecular pathways are also impacted by environmental stressors. Therefore, a genome-wide approach that links molecular mechanisms and adaptive genetic and epigenetic variation more broadly to physiological function will be necessary to understand how animals adapt to and cope with environmental uncertainty. The objective of this study is to determine how environmental variation influences adaptive genetic (DNA sequence) and epigenetic variation (DNA methylation), gene function (mRNA expression), and physiological responses (hormone activity) to shape particular phenotypes in populations of free-living superb starlings (Lamprotornis superbus) sampled across a broad-scale ecological gradient in sub-Saharan Africa encompassing some of the most unpredictable climatic zones in the world. Building upon long-term data in African starlings, and using a series of newly-established populations along an ecological gradient in Kenya, this work will allow researchers to begin to understand how environmentally-induced selection pressures shape the molecular mechanisms, adaptive evolutionary responses, and coping strategies that vertebrates use to live with environmental uncertainty.