Mechanisms underlying the evolution of salinity tolerance in fish

了解动物如何科普环境的变化，有助于更好地理解生物多样性的起源和维持，并帮助我们预测种群如何应对未来的环境变化。环境盐度是对鱼类分布和数量有很大影响的一个变量。虽然我们对鱼类在一生中科普短期盐度变化的机制了解很多，但我们对鱼类种群如何应对盐度变化的了解要少得多。我和我的学生将研究两种加拿大鱼类，四棘棘鱼（Apeltes quadracus）和带状刀鱼（Fundulus diaphanus），作为研究淡水耐受性增加的进化的模型系统。我们选择这些鱼类是因为它们在种群和物种之间具有耐盐性的多样性，它们可以很容易地从野外收集并在实验室中进行研究，并且它们与两个具有广泛基因组资源的模式物种密切相关，Threespine Stickleback（Gasterosteus aculeatus）和普通Killifish（Fundulus heteroclitus），这将有助于我们的遗传分析。我们将首先测试不同的耐盐性之间的天然种群的A。quadracus和F.透明的接下来，我们将进行综合实验，以确定与增加淡水耐受性相关的生理，分子和遗传机制，使用尖端的基因组和转录组学分析与经典的生理和定量遗传技术配对。这些研究将使我们能够测试的证据平行的机制，导致淡水耐受性之间的A。quadracus、F. diaphanus及其姊妹种G. aculeatus和F. heteroclitus，分别。然后我们将确定适应性等位基因的起源，并具体检验F。diaphanus和F. heteroclitus导致F. heteroclitus种群五名本科生和三名硕士生将在本研究期间接受培训，本研究的出版物将为我们了解动物如何适应和适应环境变化做出宝贵贡献。**

An understanding of how animals cope with changes in their environment is needed to better understand the origins and maintenance of biodiversity and help us predict how populations might respond to future environmental change. One variable that has a strong effect on the distribution and abundance of fish is environmental salinity. While we understand a great deal about the mechanisms allowing fish to cope with short-term changes in salinity within a lifetime, we know much less about how fish populations evolve in response to salinity change. My students and I will examine two species of Canadian fish, the Fourspine stickleback (Apeltes quadracus) and the Banded Killifish (Fundulus diaphanus), as models systems in which to study the evolution of increased tolerance to freshwater. We have chosen these fish because there is diversity in salinity tolerance among populations and species, they can be easily collected from the wild and studied in the lab, and they are closely related to two model species with extensive genomic resources, the Threespine Stickleback (Gasterosteus aculeatus) and the Common Killifish (Fundulus heteroclitus), which will facilitate our genetic analyses. We will first test for differences in salinity tolerance among natural populations of A. quadracus and F. diaphanus. Next, we will conduct integrative experiments to determine the physiological, molecular and genetic mechanisms associated with increased freshwater tolerance using cutting-edge genomic and transcriptomic analyses paired with classical physiological and quantitative genetic techniques. These studies will allow us to test for evidence of parallelism in the mechanisms leading to freshwater tolerance between A. quadracus, F. diaphanus and their sister species G. aculeatus and F. heteroclitus, respectively. We will then determine the origin of adaptive alleles and specifically test the hypothesis that introgressive hybridization between F. diaphanus and F. heteroclitus has led to the evolution of higher freshwater tolerance in F. heteroclitus populations. Five undergraduate and three master's students will be trained during the course of this grant and publications stemming from this research will make valuable contributions to our understanding how animals can adapt, and acclimate, to changes in their environment. **