RoL: COLLABORATIVE RESEARCH: EXTREME ENVIRONMENTS, PHYSIOLOGICAL ADAPTATION, AND THE ORIGIN OF SPECIES

极端环境可以研究生命应对远离平均环境条件的能力和局限性。富含硫化氢的泉水代表了一些最极端的淡水环境，因为硫化氢会阻止动物细胞产生能量。尽管如此，一些鱼类已经在整个美洲的硫化物泉中定居，并在这个过程中进化成新物种。该项目将研究介导鱼类耐受硫化氢能力的基因变化如何影响它们与生活在邻近淡水溪流中的相关鱼类成功杂交的能力。它涉及鉴定耐硫化氢人群和易感人群之间的遗传差异，特别是与受硫化氢毒性影响的途径相关的基因。此外，还将测试耐受群体和易感群体之间的杂种与其亲本有何不同。具体来说，将在存在或不存在硫化氢的情况下比较亲本和杂种之间的线粒体和整个生物体的功能。该项目将对环境压力的适应如何导致遗传不相容性产生新的见解，而遗传不相容性是种群之间杂交的障碍，从而了解新物种如何形成。该项目为各级高等教育的参与者提供综合生物学培训机会。它还将通过培训科学家成为有效的科学传播者并与非正式教育机构合作接触非专家受众，为科学教育和公众宣传做出贡献。自然选择驱动适应性进化并可能导致物种形成。然而，物种形成过程中内在遗传不相容性与基因流的潜在作用仍然很大程度上未知。在生理适应的背景下研究基因流的物种形成可以缩小现有的知识差距。通过对选择如何影响基因组分歧、杂种中不同基因组的重组如何影响生理功能以及这些功能后果如何影响物种形成过程的综合分析，这是可能的。该项目测试了对有毒硫化氢的生理适应与生殖隔离的出现之间联系的先验预测。它将重点关注高度保守的代谢途径氧化磷酸化（OXPHOS）的组成部分，该途径在适应硫化氢中发挥着核心作用。由于 OXPHOS 成分由线粒体和核基因组编码，理论预测 OXPHOS 的适应性修饰应引起线粒体核不相容性并有助于物种形成过程。该项目通过测试以下先验预测来研究生理适应和物种形成之间的机制联系：(1) OXPHOS 适应如何影响生活在不同环境中的种群之间的基因组差异，(2) 线粒体核不相容性在生化、生理和有机体水平上的功能后果，以及 (3) 线粒体核不相容性在物种形成过程中的相对作用。该项目采用综合方法，结合了群体基因组学、酶、细胞器和整个生物体功能的测定，以及现场和实验室实验，以量化生殖隔离的多种受精卵前后机制。该奖项由 BIO/Emerging Frontiers、DEB/Evolutionary Processes 和 IOS/Integrative Ecoological Physiology 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智力价值和更广泛的影响审查标准。

Extreme environments allow for the investigation of life's capacity and limitations to cope with far-from-average environmental conditions. Springs rich in hydrogen sulfide represent some of the most extreme freshwater environments because hydrogen sulfide halts energy production in animal cells. Nonetheless, some fish have colonized sulfide springs throughout the Americas and have evolved into new species in the process. This project will investigate how the genetic changes that mediate the fish's ability to tolerate hydrogen sulfide impact their ability to successfully interbreed with related fish that live in adjacent freshwater streams. It involves the identification of genetic differences between hydrogen sulfide-tolerant and susceptible populations, particularly in genes associated with pathways affected by hydrogen sulfide toxicity. In addition, it will be tested how hybrids between tolerant and susceptible populations differ from their parents. Specifically, the function of mitochondria and whole organisms will be compared between parents and hybrids in presence or absence of hydrogen sulfide. This project will yield new insights into how adaptation to environmental stress leads to genetic incompatibilities that represent barriers for interbreeding between populations, and thus, into how new species form. This project provides training opportunities in integrative biology for participants at all levels of higher education. It will also contribute to science education and public outreach by training scientists to become effective science communicators and reach non-expert audiences in collaboration with informal education institutions. Natural selection drives adaptive evolution and can cause speciation. However, the potential role of intrinsic genetic incompatibilities during speciation with gene flow remains largely unknown. Investigating speciation with gene flow in the context of physiological adaptation allows closing existing gaps of knowledge. This is possible through integrated analyses of how selection shapes genomic divergence, how recombination of divergent genomes in hybrids affects physiological function, and how these functional consequences affect the speciation process. This project tests a priori predictions about the links between physiological adaptation to toxic hydrogen sulfide and the emergence of reproductive isolation. It will focus on components of a highly conserved metabolic pathway, oxidative phosphorylation (OXPHOS), which plays a central role in adaptation to hydrogen sulfide. Because OXPHOS components are encoded by both the mitochondrial and the nuclear genomes, theory predicts that adaptive modification of OXPHOS should give rise to mitonuclear incompatibilities and contribute to the speciation process. This project investigates the mechanistic links between physiological adaptation and speciation by testing a priori predictions about (1) how OXPHOS adaptation affects genomic divergence between populations living in different environments, (2) the functional consequences of mitonuclear incompatibilities at the biochemical, physiological, and organismal levels, and (3) the relative role of mitonuclear incompatibilities during speciation. The project employs an integrative approach that combines population genomics, assays of enzyme, organelle, and whole organism function, as well as field and laboratory experiments for the quantification of multiple pre- and postzygotic mechanisms of reproductive isolation.This award was co-funded by BIO/Emerging Frontiers, DEB/Evolutionary Processes, and IOS/Integrative Ecological Physiology.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.