BEE: Evolutionary Responses to Global Change - Linking Genotype with Phenotype to Model Future Demography and Range Expansions

气候变化正在全球范围内引起剧烈的环境变化，包括海洋盐度的快速变化。这种盐度变化是由降雨模式的改变和大量融冰倾倒入海造成的。在高纬度地区，盐度的迅速下降给水生物种带来了难以置信的压力，以至于许多种群可能会灭绝。在水生物种中，最丰富的是浮游动物，它们是由鱼类食用的自由漂浮的浮游生物。在浮游动物中，桡足类（小甲壳类）数量最多，对沿海渔业的食物来源至关重要。这项研究将研究桡足动物种群是如何进化的，特别是自然选择是如何拯救特定种群的，并在气候变化的情况下导致物种的生存。本项目的目标是利用遗传数据和数学预测来回答以下问题：(1)面对盐度和温度的快速变化，野生种群的基因组是如何进化的？(2)盐度和温度如何影响野生种群的繁殖和生长？(3)盐度和温度的变化会迫使种群迁移还是导致它们灭绝？研究人员将通过实验室进化实验来解决这些问题，以确定在温度和盐度变化过程中，哪些基因变异（等位基因）受到自然选择的青睐。这项工作还将涉及数学模型，以了解自然选择是否有利于遗传变异，以及这是否可以拯救一个种群免于在野外灭绝。将进化整合到人口统计学的预测数学模型中，对于准确预测种群和物种的命运至关重要。这种研究特别重要，因为焦点生物（小甲壳类动物）处于食物网的基础，并支持世界各地许多重要的渔业。一名博士后、两名研究生和几名本科生（包括代表性不足的群体成员）将接受培训，进行综合研究气候变化目前正在推动全球海洋盐度的快速变化。全球水循环的剧烈变化正在导致高纬度沿海海域变新鲜，对河口产生了极其严重的影响。在这些栖息地，到2100年，预计盐度将下降5 PSU，而温度预计将上升~2-6°C。因此，预计迅速下降的盐度将成为威胁沿海人口的一个强有力的驱动因素。适应对于生存超过生理阈值的严重环境压力至关重要，但我们对自然选择的反应如何转化为人口增长率和人口统计学缺乏清楚的了解。这一提议着重于实证检验进化拯救的理论概念，即进化以足够的速度进行，以防止种群下降，从而避免灭绝和灭绝。本研究将(1)通过实验室自然选择实验（实验进化）确定对选择的反应，量化基因组对盐度和温度变化的反应（即确定等位基因的轨迹及其选择系数）；(2)通过遗传关联研究重建基因型-表型图谱，量化有益等位基因对决定绝对适合度的生活史性状的影响。最后(3)进行生态进化建模，通过将有益等位基因的进化轨迹（来自#1）和那些受选择青睐的等位基因的适合度效应（来自#2）的数据整合到预测未来人口统计的模型中，包括响应气候变化的范围变化和灭绝概率。通过阐明候选基因及其相互作用如何影响人口统计学（将基因型-表型-人口统计学联系起来），并将进化数据注入气候变化影响的预测模型，本研究将推进我们对进化适应机制的基本理解。将进化整合到人口模型中，对于准确预测未来范围变化的极限以及当地和全球物种灭绝的可能性至关重要。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。

Climate change is causing drastic environmental shifts throughout the globe, including rapid changes in ocean salinity. This salinity change is caused by alterations in rainfall patterns and enormous volumes of ice melt dumping into the seas. At higher latitudes, rapid salinity decline is imposing incredible amounts of stress on aquatic species, such that many populations are likely to go extinct. Among aquatic species the most abundant are zooplankton, which are free floating plankton eaten by fish. Among the zooplankton, copepods (small crustaceans) are the most abundant and important for providing the food source for coastal fisheries. This research will examine how copepod populations evolve and specifically how natural selection may rescue particular populations and result in the survival of species even in the face of climate change. The goal of this project is to use genetic data and mathematical predictions to answer the following questions: (1) How are the genomes of wild populations evolving when faced with rapid changes in salinity and temperature? (2) How will salinity and temperature influence reproduction and growth of wild populations? (3) Will changes in salinity and temperature force populations to migrate or cause them to go extinct? The researchers will address these questions by conducting laboratory evolution experiments to determine which genetic variants (alleles) are favored by natural selection during temperature and salinity change. The work will also involve mathematical models to understand whether natural selection favors genetic variants, and if this could rescue a population from extinction in the wild. The integration of evolution into predictive mathematical models of demography is crucial for making accurate predictions of the fate of populations and species. Such research is especially important because the focal organisms (small crustaceans) are at the base of the food web and support many important fisheries throughout the world. One postdoctoral fellow, two graduate students, and several undergraduate students (including members of under-represented groups) will be trained in conducting integrative research Climate change is currently driving rapid changes in ocean salinity throughout the world. Drastic changes in the global water cycle are causing the freshening of high latitude coastal seas, with acutely severe impacts on estuaries. In such habitats, by the year 2100, salinity is projected to decline by up to 5 PSU, while temperatures are expected to rise by ~2-6°C. Thus, rapidly declining salinity is predicted to become a potent driver threatening coastal populations. Adaptation is critical for surviving severe environmental stress that exceeds physiological thresholds, but we lack clear understanding of how responses to natural selection translate to population growth rate and demography. This proposal focuses on empirically testing the mostly theoretical concept of evolutionary rescue, where evolution proceeds with sufficient speed to forestall population decline so extirpation and extinction do not occur. The research will (1) determine the Response to Selection, by conducting laboratory natural selection experiments (experimental evolution) to quantify the genomic responses to salinity and temperature change (i.e., determine the trajectory of alleles and their selection coefficients) and then (2) reconstruct the Genotype-Phenotype Map, by performing genetic association studies, to quantify the effects of beneficial alleles on life history traits that determine absolute fitness, and finally (3) perform Eco-Evolutionary Modeling, by incorporating data on evolutionary trajectories of beneficial alleles (from #1) and fitness effects of those alleles favored by selection (from #2) into models that predict future population demography, including range shifts and probability of extinctions in response to climate change. This study will advance our fundamental understanding of mechanisms of evolutionary adaptation, by elucidating how candidate genes and their interactions could affect demography (linking genotype-phenotype-demography) and by injecting evolutionary data into predictive models of climate change impacts. Such an integration of evolution into demographic models is crucial for making accurate predictions on limits to future range shifts and probabilities of local and global extinctions.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.