Collaborative Research: Patterns of Larval Dispersal and Postsettlement Selection Shaping Connectivity of Oyster Populations Along an Ecotone

合作研究：幼体扩散和定居后选择的模式塑造生态交错带沿线牡蛎种群的连通性

• 批准号: 0648528
• 负责人: Matthew Hare
• 金额: $ 84.8万
• 依托单位: University of Maryland, College Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-04-01 至 2008-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0648528&HistoricalAwards=false
• 关键词: Collaborative; Research; Patterns; Larval; Dispersal

Population persistence and the scale of local adaptation are determined by both larval connectivity and post-settlement selection when habitats are spatially heterogeneous for growth and/or reproduction. Unfortunately, the relative importance of factors acting before and after settlement that limit recruitment and gene flow is still unknown for most species and most marine ecosystems. This is partly because the interactions between larval behavior and hydrography are difficult to study, so dispersal constraints are only inferred indirectly. In addition, many marine species are not amenable to strong spatial tests of post-settlement selection and these experiments are difficult to accomplish at the large spatial scales relevant to high dispersal species. Consequently, only a handful of natural systems have yielded results that distinguish pre- and post-settlement constraints on gene flow such that our understanding of mechanisms generating genetic and phenotypic population structure is piece meal. The intellectual merit of the study is that it achieves this dual goal in an estuarine species inhabiting semi-connected lagoons along eastern Florida where there is a latitudinal gradient in environmental variables, community composition, and potential larval dispersal vectors. Much of the western North Atlantic coastline includes shallow lagoons enclosed by barrier islands, but only a handful of studies have measured connectivity among estuaries, and none among lagoons. This project builds on significant previous research on the eastern oyster, Crassostrea Virginica to integrate pre- and post-settlement measurements. High resolution genetic identification of migrants will be used to construct a connectivity matrix among 30 populations in each of three years. Statistical associations will be tested between dispersal patterns and hypothesized dispersal vectors and constraints. Cohort analysis will be used to test for spatial variation in genotype-specific survivorship along the entire coast. Also, in each of two years, relative postsettlement survivorship and performance will be measured in field common gardens in which local individuals, migrants and hybrids are compared. Finally, fertilization efficiency of within- and between-population crosses will be compared to test the hypothesis that gamete incompatibilities limit gene flow. The results will be integrated in models that describe the spatially and/or temporally dynamic balance between dispersal and selection, define the spatial scale of local adaptation along the ecotone, and identify abiotic gene flow constraints that may affect codistributed species.The broader impacts of this study derive from its focus on important habitats for diversity and fisheries management, and on the involvement of underrepresented groups. The oyster populations under study inhabit eastern Florida lagoons that possess the highest diversity of any estuary in the United States, yet this coastline is undergoing rapid development. In addition, the Cape Canaveral lagoons contain the oldest marine protected area in North America. Understanding the impact of this reserve on surrounding fished populations hinges on dispersal across its boundaries and on habitat quality, both of which are studied here. This study will also support one PhD student who will focus on the measurements of selection for her dissertation. The graduate student is a female African-American who endeavors to study marine evolutionary ecology, a goal spanning two fields with extremely low minority representation. The P.I. has a continuing interest in attracting the next generation of scholars. Currently four undergraduates work in the Hare lab on projects related to the Florida ecotone. Three of the undergraduates are women and the fourth an African-American. Funding from NSF will allow undergraduate participation to be expanded to include summer field work in Florida. Previous undergraduates working in the Hare lab have obtained Howard Hughes fellowships and contributed to publications (Gaines et al. 2005). The University of Maryland graduates more African-Americans than any of the top 20 universities in this country. This provides a large pool of minority candidates for possible recruitment to the Hare lab. The P.I. has a history of integrating primary research results into lectures in introductory genetics. Research results are also disseminated via lab web page postings.

当生境在生长和/或繁殖方面具有空间异质性时，种群持久性和局部适应规模由幼虫连通性和定居后选择共同决定。不幸的是，对于大多数物种和大多数海洋生态系统来说，在定居前后限制招募和基因流动的因素的相对重要性仍然未知。这部分是因为幼虫行为和水文之间的相互作用很难研究，因此只能间接推断出扩散约束。此外，许多海洋物种不适应强大的定居后选择的空间测试，这些实验难以在与高分散物种相关的大空间尺度上完成。因此，只有少数自然系统产生了区分定居前和定居后基因流动限制的结果，使得我们对产生遗传和表型群体结构的机制的理解是零碎的。该研究的智力价值在于，它在居住在佛罗里达州东部半连通泻湖的河口物种中实现了这一双重目标，该泻湖在环境变量、群落组成和潜在的幼虫传播媒介方面存在纬度梯度。北大西洋西部海岸线的大部分地区都有被堰洲岛包围的浅泻湖，但只有少数研究测量了河口之间的连通性，而泻湖之间的连通性则没有。该项目建立在之前对东部牡蛎的重要研究基础上，整合了沉降前和沉降后的测量。移民的高分辨率遗传鉴定将用于构建每三年30个人口之间的连通性矩阵。将测试分布模式与假设的分布向量和约束之间的统计关联。队列分析将用于测试整个沿海地区基因型特异性生存率的空间差异。此外，每两年，将在田间公共花园中测量相对的定居后存活率和表现，其中比较当地个体，移民和杂交品种。最后，将比较种群内和种群间杂交的受精效率，以验证配子不亲和性限制基因流动的假设。研究结果将被整合到描述分散和选择之间的空间和/或时间动态平衡的模型中，定义沿交错带的局部适应的空间尺度，并确定可能影响共分布物种的非生物基因流约束。这项研究的更广泛的影响源于它侧重于多样性和渔业管理的重要生境，以及代表性不足的群体的参与。被研究的牡蛎种群居住在佛罗里达州东部的泻湖，那里拥有美国河口中最高的多样性，然而这条海岸线正在快速发展。此外，卡纳维拉尔角泻湖拥有北美最古老的海洋保护区。了解这个保护区对周围鱼类种群的影响取决于在其边界上的分散和栖息地质量，这两者都是这里研究的。这项研究还将支持一名博士生，她将专注于她的论文选择的测量。这名研究生是一名非裔美国女性，她致力于研究海洋进化生态学，这是一个跨越两个领域的目标，少数族裔的代表性极低。私家侦探一直对吸引下一代学者感兴趣。目前有四名本科生在Hare实验室从事与佛罗里达过渡带有关的项目。其中三名本科生是女性，第四名是非裔美国人。来自美国国家科学基金会的资助将允许本科生参与到佛罗里达的夏季野外工作中。之前在Hare实验室工作的本科生都获得了Howard Hughes奖学金，并发表了论文（Gaines et al. 2005）。马里兰大学毕业的非裔美国人比全国排名前20的大学都多。这为海尔实验室提供了大量的少数族裔候选人。私家侦探有将初级研究成果纳入遗传学入门讲座的历史。研究成果也通过实验室网页发布。