Collaborative Research: LTREB: BEE: Long-term ecological and evolutionary dynamics of secondary contact.

动植物种群经常被自然过程和人类活动隔绝。与世隔绝，种群适应当地环境，特征和基因可能会分化。这种适应性差异可能会产生重要的生态变异，从而改变物种在生态系统中的角色。自然过程和人类活动也可以允许或迫使孤立的人群重新接触--这一过程被称为二次接触。二次接触的结果对于了解种群的进化和生态系统的功能很重要。这个LTREB利用一个全湖恢复项目来研究最近分化的妻子血统之间二次接触的十年尺度的生态和进化动力学。银鱼是一种经过充分研究的重要生态鱼类，产于北美东部的湖泊和沿海海域。有两种不同的妻子生活史形式：一种是在湖泊和沿海海洋之间活动的祖先滨水形式，另一种是居住在湖泊中的内陆形式。许多内陆人口是由殖民地美国人修建水坝形成的。最近拆除水坝和修建渔道为内陆和退水期妇女人口之间的二次接触创造了机会。研究结果将涉及对生物多样性的产生和维持至关重要的问题，物种内变异的生态影响，以及人类加速的环境变化的影响，包括种群碎片化、栖息地连通性的恢复和气候变化。该项目将为滨水区的养护和管理提供信息，这是沿海淡水和海洋生物栖息地的关键资源，是受保护关注的物种，也是密集恢复和养护工作的重点。该项目开发的基因组工具将帮助资源管理者解决重要的问题，例如兼捕对水母种群的影响。该项目将培训研究生和本科生，包括来自代表性不足的背景的学生，以先进的基因组技术和全湖采样的独特组合。该项目研究气候变化、后水交配母羊种群恢复和周期性主要杂交事件(每十年2-3次)如何相互作用，以确定杂交的大小和基因流动的方向，交配母羊类型之间的表型分化，以及整个湖泊的影响。重点是修复康涅狄格州罗杰斯湖和区域参照湖。该项目利用信息量高的微型单倍型遗传标记来测量杂交和基因流；测量营养形态、个体生长速度、饮食和栖息地利用来评估形式之间的表型和生态差异；以及采样无机营养物质、浮游植物和浮游动物来评估整个湖泊的影响。这项研究提供了一个难得的机会来追踪从二次接触开始的生态和进化动态，长期研究计划有助于在整个生态系统规模上发现罕见事件以及生态和进化过程之间的相互作用。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Populations of animals and plants are regularly isolated by natural processes and human activities. In isolation, populations adapt to local environments, and traits and genes may diverge. This adaptive divergence can create ecologically important variation that changes the role of species within ecosystems. Natural processes and human activities can also allow or force populations that have diverged in isolation to come back into contact - a process called secondary contact. The outcome of secondary contact is important for understanding how populations evolve and ecosystems function. This LTREB takes advantage of a whole-lake restoration project to study the decade-scale ecological and evolutionary dynamics of secondary contact between recently diverged lineages of alewife. Alewife are a well-studied and ecologically important fish found in lakes and in the coastal ocean of eastern North America. There are 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. Many landlocked populations were formed by the construction of dams by colonial Americans. The recent removal of dams and construction of fishways create opportunities for secondary contact between landlocked and anadromous alewife populations. Findings will address questions fundamental to the generation and maintenance of biodiversity, the ecological impact of variation within species, and the impacts of human accelerated environmental changes including population fragmentation, restoration of habitat connectivity, and climate change. This project will inform the conservation and management of anadromous alewife, a critical resource in coastal freshwater and marine habitats, a species of conservation concern, and the focus of intensive restoration and conservation efforts. The genomic tools developed by this project will help resource managers address important questions, such as the impact of bycatch on anadromous alewife populations. The project will train graduate and undergraduate students, including students from underrepresented backgrounds, in a unique combination of advanced genomics techniques and whole-lake sampling. This project asks how climate change, anadromous alewife population recovery, and periodic major hybridization events (2-3 per decade), interact to determine the magnitude of hybridization and direction of gene flow, phenotypic differentiation among alewife forms, and whole-lake impacts. It focuses on the restoration of Rogers Lake, Connecticut and regional reference lakes. This project utilizes highly informative microhaplotype genetic markers to measure hybridization and gene flow; measures trophic morphology, individual growth rates, diets, and habitat use to assess phenotypic and ecological differentiation among forms; and samples inorganic nutrients, phytoplankton, and zooplankton to evaluate whole-lake impacts. This research provides a rare opportunity to track the ecological and evolutionary dynamics from the initiation of secondary contact, and the long-term research plan facilitates the detection of rare events and interactions between ecological and evolutionary process at the whole ecosystem scale.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.