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: 1121832
• 负责人: Michael Tobler
• 金额: $ 48.09万
• 依托单位: Oklahoma State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-01 至 2014-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1121832&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.

硫化氢是一种剧毒气体，即使浓度很低，对大多数动物也是致命的。在墨西哥南部，Poecilia属的小型活鱼独立地定居在多个硫化氢泉中，那里的硫化氢自然浓度很高。这些鱼提供了一个机会来研究脊椎动物是如何在对大多数其他生物来说是致命的环境中生存下来的。硫化物泉的适应也导致了硫化物和非硫化物生态型之间的生殖隔离，为新物种的进化提供了见解。本提案的目的是确定在硫化氢和非硫化氢栖息地的复制对中表型和遗传分化的趋同模式。这种比较将揭示两个性状和潜在的遗传变化介导硫耐受。该研究解决了三个基本问题：(1)复杂表型如何沿着复制的环境梯度进化？量化野生捕获个体的表型变异（包括行为、生理和形态特征）将确定硫化氢鱼和非硫化氢鱼复制对中适应性性状分化的趋同模式。分析普通花园栽培个体的相同表型性状，将有助于揭示遗传分化和表型可塑性如何相互作用以表达自然界的表型。(2)性状分化背后的基因组变化是什么？下一代测序技术（RNA-Seq）将被用于识别那些表现出不同选择或差异表达特征的基因，这些特征将被用于识别适应极端环境的候选基因。(3)不同环境条件下表达的不同性状对生殖隔离的功能影响是什么？比较实验室饲养的鱼在硫化物和非硫化物条件下的生长速度，将提供对硫化物的适应和以移民无法生存的形式出现的生殖隔离之间的直接联系。理解生物?对自然发生的压力环境的反应最终可以用来更好地理解人为改变环境的生物体反应的原因和后果。该项目促进了来自美国和墨西哥的科学家和学生在研究和教育方面的合作。本项目为鱼类生物学家建立一个与鱼类爱好者组织互动的公共推广平台，将研究成果传播给公众。