Collaborative Research: Comparative genomics and physiology to discover integrated mechanisms that support phenotypic plasticity

大多数物种都适应在相对稳定的环境中生活。很少有物种能忍受剧烈波动的环境。物种在高度多变的环境中生存和繁衍所需的生理灵活性是由什么驱动的，我们知之甚少。这项研究将使用为北美鳉鱼开发的遗传和生理工具和方法，以获得对极端生理灵活性如何组装及其工作原理的综合理解。在底藻属中，有些鱼类非常灵活，可以适应极端的环境盐度，但其他鱼类的灵活性要差得多。对于多对物种，将高灵活性物种与密切相关的低灵活性物种进行比较。这种比较方法对于区分高灵活性物种的独特之处非常有效。研究结果将为基因组特征（基因序列的变异、遗传控制元件的变异、基因含量的变异）如何启用或禁用对极端环境变化的生理调节提供新的见解。全球气候变化的一个标志是环境变异性的频率和严重程度增加，而这种变异性正在对全球生物多样性危机构成另一种威胁。这项研究应该能让我们深入了解是什么让一些物种在面对环境变化时表现得更好。该项目由综合生态生理学和促进竞争研究的既定计划（EPSCoR）共同资助。作为表型可塑性的一种重要形式，支持生理灵活性的基因组基础结构可能是复杂和多基因的，但人们对其了解甚少。大多数水生物种生活在渗透性稳定的淡水或咸水（海洋）中，这些水域的盐度变化不大，居民对适应盐度变化的限制很窄，被认为是“窄盐”。相比之下，广盐物种可以调整生理机能以适应盐度的巨大变化；它们在河口等渗透动态环境中生存并茁壮成长。泛盐性是一种非常重要的表型可塑性形式。整合生理、转录组学和结构基因组信息的比较实验将用于揭示支持全卤性的机制基础设施。底鳉属包括许多种类的广盐河口特种鱼。对淡水的多次独立辐射也导致了盐度的反复损失。生理挑战实验将在系统发育-比较框架内使用，其中三个分支中独立进化的可塑性损失提供了重复的机会来推断支持祖先保留的可塑性的机制。实验将检验euryhalinity是由自然选择维持和限制的基因调控灵活性所支撑的假设。这项工作将阐明一个在生理学上和脊椎动物多样化史上都很重要的特征的机制基础。由于全盐性也是表型可塑性的一个引人注目的例子，这些发现将有助于阐述表型可塑性的机制和分子遗传基础的日益增长的一般理论。该项目由综合生态生理学和促进竞争研究的既定计划（EPSCoR）共同资助。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Most species are adapted to live in relatively stable environments. Rare are those species that tolerate environments that fluctuate rapidly and severely. Little is known about what drives the physiological flexibility needed for species to survive and thrive in highly variable environments. This research will use genetic and physiological tools and approaches developed for North American killifish to gain an integrative understanding of how extreme physiological flexibility is assembled and how it works. Within the Fundulus genus, some species of fish are highly flexible and can adjust to huge extremes in environmental salinity, but others are much less flexible. High-flexibility species are compared to closely-related low-flexibility species, for multiple pairs of species. This comparative approach is powerful for distinguishing what makes high-flexibility species unique. Results should provide new insights into how features of the genome (variation in gene sequences, variation in genetic control elements, variation in gene content) may enable or disable physiological adjustments to extreme environmental change. One hallmark of global climate change is an increase in the frequency and severity of environmental variability, and this variability is posing yet another threat to the global biodiversity crisis. This research should provide insights into what makes some species more or less likely to do well in the face of environmental variability. This project is jointly funded by Integrative Ecological Physiology and the Established Program to Stimulate Competitive Research (EPSCoR).The genomic infrastructure that supports physiological flexibility, an important form of phenotypic plasticity, is likely complex and multigenic but is poorly understood. Most aquatic species live in osmotically stable fresh or salty (marine) waters which vary little in salinity, where residents exhibit narrow limits for accommodating salinity changes and are considered “stenohaline”. In contrast, euryhaline species can adjust their physiology to accommodate large changes in salinity; they survive and thrive in osmotically dynamic environments such as estuaries. Euryhalinity is an extraordinary and important form of phenotypic plasticity. Comparative experiments that integrate physiological, transcriptomic, and structural genomic information, will be used to reveal the mechanistic infrastructure that supports euryhalinity. The Fundulus genus of killifish includes many species of euryhaline estuarine specialists. Multiple independent radiations into fresh water have also resulted in repeated losses of euryhalinity. Physiological challenge experiments will be used, within a phylogenetic-comparative framework where independently evolved losses of plasticity in three clades provide replicated opportunities to infer the mechanisms that support plasticity that is ancestrally retained. Experiments will test the hypothesis that euryhalinity is underpinned by gene regulatory flexibility maintained and constrained by natural selection. This work will illuminate the mechanistic basis of a trait that is both physiologically important, and important in the history of vertebrate diversification. Since euryhalinity is also a compelling example of phenotypic plasticity, findings will contribute to the elaboration of a growing general theory of the mechanistic and molecular-genetic basis of phenotypic plasticity. This project is jointly funded by Integrative Ecological Physiology and the Established Program to Stimulate Competitive Research (EPSCoR).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.