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

大多数物种都能适应相对稳定的环境。很少有物种能忍受快速而剧烈波动的环境。关于是什么驱动了物种在高度多变的环境中生存和繁荣所需的生理灵活性，人们知之甚少。这项研究将使用遗传和生理工具和方法开发的北美鳉鱼，以获得一个综合的了解如何极端的生理灵活性组装和它是如何工作的。在底属中，有些种类的鱼非常灵活，可以适应极端的环境盐度，但其他种类的鱼就不那么灵活了。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。结果应该提供新的见解，基因组的功能（基因序列的变化，遗传控制元件的变化，基因内容的变化）可能会启用或禁用生理调整极端的环境变化。全球气候变化的一个标志是环境变异的频率和严重性增加，而这种变异对全球生物多样性危机构成又一个威胁。这项研究应该能让我们深入了解是什么让某些物种在面对环境变化时或多或少地表现良好。该项目由整合生态生理学和刺激竞争研究的既定计划（EPSCoR）共同资助。支持生理灵活性的基因组基础设施是表型可塑性的重要形式，可能是复杂的和多基因的，但知之甚少。大多数水生物种生活在盐度变化很小的生态稳定的淡水或咸水（海洋）沃茨，其中居民表现出适应盐度变化的狭窄限制，被认为是“狭盐”。相比之下，广盐性物种可以调整其生理机能以适应盐度的巨大变化;它们在河口等动态环境中生存和繁荣。广盐性是表型可塑性的一种特殊而重要的形式。比较实验，整合生理，转录组学和结构基因组信息，将被用来揭示支持广盐性的机械基础设施。基属的鳉鱼包括许多广盐性河口专家的物种。对淡水的多次独立辐射也导致广盐性的反复丧失。将使用生理挑战实验，在一个遗传学比较框架内，独立进化的可塑性损失在三个分支提供复制的机会来推断机制，支持可塑性是祖先保留。实验将检验这一假设，即广盐性是由自然选择维持和约束的基因调控灵活性所支撑的。这项工作将阐明一个特性的机械基础，这是生理上的重要性，并在脊椎动物多样化的历史上很重要。由于广盐性也是一个引人注目的例子，表型可塑性，研究结果将有助于制定一个不断增长的一般理论的机械和分子遗传基础的表型可塑性。该项目由综合生态生理学和刺激竞争研究的既定计划（EPSCoR）共同资助。该奖项反映了NSF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.