Evolutionary Responses to Global Changes in Salinity and Temperature

全球水循环的急剧变化和冰融化的增加正在造成北方沿海海洋的淡化。盐度降低和温度升高的结合可能会共同减少河口和海洋生物的数量。数据表明，降低盐度和高温将分别增加能源成本，以及减少常见的桡足类Eurytemora affinis的生存和繁殖。本研究将探讨盐度降低和温度升高对E. affinis在野外，以及在实验室的选择实验。这项研究将为生物体对气候变化的反应提供新的见解，因为没有研究分析盐度和温度对进化反应的联合影响，并且相对较少的研究研究了盐度下降的影响。一般来说，选择如何在整个基因组水平上起作用还没有很好的理解，特别是对于非模式生物。作为河口桡足类的优势种，E. affinis是维持北方半球沿海食物网和渔业的最重要物种之一，如鲑鱼、鲱鱼和鱼。因此，深入了解其对气候变化的进化反应对渔业和粮食安全的可持续性具有重要意义。在这个项目期间，将培训两名来自历史上代表性不足群体的研究生。该项目还将产生其他社会效益，包括为K-12学生开发教育模块和国际合作。 本研究将探讨以下问题：（1）种群对盐度和温度变化的响应程度，以及适应度和生理代价是什么？(2)人口将如何应对盐度-温度相互作用的影响？(3)野生种群是否表现出自然选择对盐度和温度的反应？分析E.为了研究affinis种群对盐度和温度的耦合影响，研究人员将进行实验室选择实验和野生种群的种群基因组调查。选择实验是确定适应的速度、轨迹和限度的有力工具。在实验室选择过程中，将研究与适应性相关的性状和基因组表达的进化变化，以及低盐度和高温选择制度下选择的基因组特征。研究者还将进行E. affinis种群居住在沿着盐度和温度梯度在圣劳伦斯海和波罗的海，并确定基因，显示签名的选择。该项目将确定在野生种群中显示选择特征的基因座是否与实验室选择中所青睐的基因座相同。这种再现性将提供更大的信心，参与适应盐度和/或温度的基因已被捕获。

Drastic changes in the global water cycle and increases in ice melt are causing the freshening of Northern coastal seas. The combination of both reduced salinity and increased temperature will likely act in concert to reduce populations of estuarine and marine organisms. Data indicate that reduced salinity and high temperature would each increase the energy costs as well as reduce survival and reproduction of the common copepod Eurytemora affinis. This project will examine the joint effects of salinity reduction and temperature increase on the evolutionary responses of populations of E. affinis in the wild, as well as in selection experiments in the laboratory. This study will provide novel insights into responses of organisms to climate change, as no study has analyzed the joint impacts of salinity and temperature on evolutionary responses, and relatively few studies have examined the impacts of declining salinity. In general, how selection acts at the whole genome level is not well understood, particularly for non-model organisms. As a dominant estuarine copepod, E. affinis is among the most important species sustaining coastal food webs and fisheries in the Northern Hemisphere, such as salmon, herring, and anchovy. Thus, insights into its evolutionary responses with changing climate have important implications for sustainability of fisheries and food security. Two graduate students from historically underrepresented groups will be trained during this project. The project will have additional societal benefits, including development of educational modules for K-12 students and international collaboration. This study will address the following questions: (1) To what extent could populations evolve in response to salinity and temperature change, and what are the fitness and physiological costs? (2) How will populations respond to the impacts of salinity-temperature interactions? (3) Do wild populations show evidence of natural selection in response to salinity and temperature? To analyze the evolutionary responses of E. affinis populations to the coupled impacts of salinity and temperature, the investigator will perform laboratory selection experiments and population genomic surveys of wild populations. Selection experiments constitute powerful tools for determining the rate, trajectory, and limits of adaptation. During laboratory selection, evolutionary shifts in fitness-related traits and genomic expression will be examined, as well as genomic signatures of selection in response to low salinity and high temperature selection regimes. The investigator will also conduct population genomic sequencing of E. affinis populations that reside along salinity and temperature gradients in the St. Lawrence and Baltic Sea, and identify genes that show signatures of selection. The project will determine whether the loci that show signatures of selection in the wild populations are the same as those favored during laboratory selection. This reproducibility will provide greater confidence that the genes involved in adaptation to salinity and/or temperature have been captured.