Replicated Ecological Speciation in Extreme Habitats: Patterns, Mechanisms, and Consequences of Multi-Trait Divergence

极端栖息地中复制的生态物种形成：多性状分化的模式、机制和后果

• 批准号: 1463720
• 负责人: Michael Tobler
• 金额: $ 22.15万
• 依托单位: Kansas State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-01 至 2015-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1463720&HistoricalAwards=false
• 关键词: Replicated; Ecological; Speciation; Extreme; Habitats

Hydrogen sulfide is a highly toxic gas that is lethal for most animals, even at low concentrations. In southern Mexico, small livebearing fish of the genus Poecilia have independently colonized multiple sulfidic springs, where hydrogen sulfide naturally occurs in high concentrations. These fish provide an opportunity to study how vertebrates have managed to survive in conditions that are lethal for most other organisms. Adaptation in sulfide springs also leads to reproductive isolation between sulfidic and non-sulfidic ecotypes, providing insights about how new species evolve. The objectives of this proposal are to identify convergent patterns of phenotypic and genetic differentiation in replicated pairs of sulfidic and non-sulfidic habitats. This comparison will reveal both traits and the underlying genetic changes that mediate sulfide tolerance. The research addresses three basic questions: (1) How do complex phenotypes evolve along replicated environmental gradients? Quantifying phenotypic variation (including behavioral, physiological, and morphological traits) in wild-caught individuals will identify convergent patterns of adaptive trait divergence in replicated pairs of sulfidic and non-sulfidic fish. Analyzing the same phenotypic traits in common garden-raised individuals will shed light on how heritable differentiation and phenotypic plasticity interact to express phenotypes in nature. (2) What are the genomic changes underlying trait divergence? Next generation sequencing technologies (RNA-Seq) will be used to identify genes that show signatures of divergent selection or differential expression, which will be used to identify candidate genes underlying adaptation to the extreme environments. (3) What are the functional consequences of the divergent traits expressed under different environmental conditions for reproductive isolation? Comparing growth rates of laboratory-reared fish exposed to either sulfidic or non-sulfidic conditions will provide a direct link between adaptation to sulfide and reproductive isolation in the form of immigrant inviability. Understanding organisms? responses to naturally occurring stressful environments can ultimately be used to better understand causes and consequences of organismal responses to anthropogenically altered environments. The project fosters collaboration in research and education between scientists and students from the United States and Mexico. This project establishes a public outreach platform for fish biologists to interact with fish hobbyist organizations as a means to disseminate research findings to the lay public.

硫化氢是一种剧毒的气体，即使在低浓度下，对于大多数动物来说都是致命的。在墨西哥南部，poecilia属的小小的活鱼鱼独立定居多个硫化弹簧，那里的硫化氢自然地以高浓度发生。这些鱼提供了研究脊椎动物如何在大多数其他生物具有致命疾病的疾病中生存的机会。硫化物弹簧的适应还导致硫化和非硫化生态型之间的生殖分离，从而提供了有关新物种如何发展的见解。该提案的目标是确定在硫酸和非硫化栖息地的复制对中表型和遗传分化的收敛模式。这种比较将揭示性状和介导硫化物耐受性的潜在遗传变化。该研究解决了三个基本问题：（1）复杂的表型如何沿着复制的环境梯度发展？野生捕获的个体中量化表型变异（包括行为，生理和形态性状）将在复制的硫酸和非硫化鱼类对中识别自适应性状差异的收敛模式。分析普通花园饲养的个体中相同的表型特征将阐明遗传分化和表型可塑性在自然界中表达表型的相互作用。 （2）性状差异的基因组变化是什么？下一代测序技术（RNA-SEQ）将用于识别显示出不同选择或差异表达的特征的基因，这些基因将用于识别对极端环境适应的候选基因。 （3）在生殖隔离的不同环境条件下表达的不同特征的功能后果是什么？比较暴露于硫酸或非硫化条件的实验室饲养鱼的生长速率将以移民不可分割的形式在适应对硫化物和生殖隔离之间的直接联系。了解生物？对自然发生的压力环境的反应最终可以用来更好地理解生物对人为改变环境的生物反应的原因和后果。该项目促进了美国和墨西哥科学家与学生之间研究和教育的合作。该项目为鱼类生物学家建立了一个公共外展平台，以与鱼类业余爱好者组织互动，以此作为向外行公众传播研究结果的一种手段。