COLLABORATIVE RESEARCH: Ecological and evolutionary dynamics of secondary contact

通过拆除水坝，全国的河流和溪流正在恢复到原来的流动模式，许多水坝是几个世纪前建造的，为小型磨坊提供能源，这些磨坊是殖民地经济的基础。该项目利用了计划中的大坝拆除，将分离了近四个世纪的鱼群连接起来，以研究这些最近分化的鱼群之间的二次接触的生态和进化后果，这些鱼群可能会杂交，也可能会竞争。这项工作的结果将有助于保护和管理洄游的灰西鲱，这是沿海淡水和海洋栖息地的重要资源，也是强化恢复和保护工作的重点。研究人员将与州管理者、康涅狄格州能源和环境保护部、湖泊协会和土地信托机构合作，确定恢复迁徙种群的后果，提供对大灰鲱恢复至关重要的信息，并向当地社区宣传河流恢复的后果。该项目将培养一名博士后研究员，以及研究生和本科生，通过一个跨学科的项目，依靠先进的遗传学技术，现场采样，以及操作现场和实验室实验。耶鲁大学现有的一个项目将支持未被充分代表的少数族裔本科生参与暑期研究。培训将包括研究的更广泛的科学背景、研究方法、数据分析、书面和口头项目报告，以及与公众直接接触以展示研究的社会效益。本项目利用全湖恢复工程的优势，了解新近分化的alewife谱系之间次生接触的生态和进化动态。大坝建设造成的隔离导致了两种不同的大灰鲭鱼生活史形式：在湖泊和沿海海洋之间移动的祖先溯河形式和居住在湖泊中的内陆形式。该项目将结合先进的基因组学、小规模实验、全湖观察和实验来记录和理解二次接触的后果，当大坝拆除时，产卵的大灰鲱重新被引入含有内陆形式的湖泊。与拆除大坝的国家机构密切合作，将使调查人员能够研究从其开始的二次接触。该项目研究了对次生接触的三个反应阶段：浮游生物群落和养分流动的快速生态变化，无脊椎动物种群对新生态条件的快速进化反应，两种大灰鲟之间可能导致杂交的相互作用，以及从长远来看，大灰鲟的进化和当地适应。第一种反应——湖泊群落的生态变化——对于解释由此产生的进化变化至关重要。该项目的独特之处在于它能够在两个时间尺度上捕捉二次接触的后果。研究结果将对次生接触后野外种群的生态和进化过程之间的反馈提供难得的见解，对恢复生态系统的生态系统功能和生物多样性的维持具有重要意义。

Rivers and streams across the country are being restored to their original flow patterns by the removal of dams, many of which were constructed centuries ago to provide energy for small mills that formed the basis of colonial economies. This project takes advantage of planned dam removals that will connect fish populations that have been separated for nearly four centuries, in order to study the ecological and evolutionary consequences of secondary contact between these recently divergent fish populations, which may interbreed but also may compete. Results from this work will contribute to the conservation and management of migratory alewife fish, a critical resource in coastal freshwater and marine habitats and the focus of intensive restoration and conservation efforts. Researchers will work collaboratively with state managers, the Connecticut Department of Energy and Environmental Protection, lake associations, and land trusts to determine the consequences of restoring migratory populations, provide information vital to alewife recovery, and educate local communities on the consequences of river restoration. The project will train a postdoctoral researcher along with graduate and undergraduate students in an interdisciplinary project that relies on advanced genetics techniques, field sampling, and manipulative field and laboratory experiments. An existing program at Yale University will support involvement of underrepresented minority undergraduate students in summer research. Training will include the broader scientific context of the research, research methods, data analysis, written and oral project reports, and direct involvement with the public to present the societal benefits of the research. This project takes advantage of whole-lake restoration projects to understand the ecological and evolutionary dynamics of secondary contact between recently diverged lineages of alewife. Isolation caused by construction of dams has resulted in two divergent alewife life history forms: the ancestral anadromous form that moves between lakes and the coastal ocean and a landlocked form that is resident in lakes. This project will combine advanced genomics, small-scale experiments, and whole-lake observations and experiments to document and understand the consequences of secondary contact, when dam removal allows reintroduction of anadromous alewife into lakes that contain the land-locked form. Close collaboration with the state agency that removes dams will allow the investigators to study secondary contact from its initiation. The project addresses three stages in response to secondary contact: rapid ecological change in planktonic communities and nutrient flux, rapid evolutionary responses in invertebrate populations in response to novel ecological conditions, and interactions between the two alewife morphs that may result in hybridization and, over the longer-term, alewife evolution and local adaptation. The first of these responses - ecological changes in lacustrine communities - is essential in order to interpret the evolutionary changes that result. The project is unique in its ability to capture the consequences of secondary contact on both time scales. Results will provide rare insight into feedbacks between ecological and evolutionary processes in field populations following secondary contact with important implications for ecosystem function and the maintenance of biodiversity in restored ecosystems.