Collaborative Research: Evaluating Marine Clines to Predict Larval Retention

智力优势：尽管推断海洋种群间基因流动的分析取得了很大进展，但仍然难以确定维持种群空间变异的种群或机制，或维持具有浮游幼虫的物种的连通性。 新的多样性是如何保留在似乎是混合良好的海洋系统是知之甚少，特别是选择和扩散之间的平衡，影响这些物种的遗传变异模式。 本研究探讨了不对称扩散对海洋多样性的影响，一般来说，并在藤壶Notochthalus scabrosus沿着智利海岸，特别是。 从本质上讲，这项研究的重点是电流如何影响的地理和海洋地理模式的底栖无脊椎动物与浮游幼虫。 在这一地区，有一个遗传渐变的这个物种，可能代表性能为基础的藤壶的两个不同的谱系之间的差异，在近岸海洋学和潮间带生态的过渡。 的机制，让渐变群坚持面对幼虫扩散将进行定量测试。 该研究将有助于提高N. scabrosus，检查潜在的选择梯度，并比较间接估计的不对称基因流与环境隔离模型，连接物理海洋学和海洋地理学。 这项研究将是对最近由PI开发的地理学和种群遗传模型所作预测的第一次经验性探索，这些模型是遗传结构在沿海海洋中持续存在的必要条件。 该项目的独创性在于，它不是仅仅依靠地理学推断来预测各种未经检验的假设下的种群连接，而是将物理和生物数据相结合，以确定维持沿海多样性的具体机制。 这项研究将连接动力学维持N。scabrosus倾向于智利同事积极研究的其他海洋物种的模式，并将有助于验证当前沿海岸沿着的幼虫的建模工作。 此外，与智利同事合作将有效地获得和分析本研究所需的数据。 把重点放在智利海岸有很多好处，包括它与研究得很好的俄勒冈州和加州海岸的有趣相似性，可能允许从这项工作的结果中进行概括。 最重要的是，这项工作将推动源-汇动态从理论文献到人口模式如何分布和维持在一个物种的范围内的基础研究，与理解的结构和动态范围限制本身的影响。 这项工作将根据人口和基因流分析，结合海洋学特征，确定智利海岸沿着可能的源种群，并提供一个框架，可用于沿着任何海岸的类似工作（例如，美国太平洋沿岸），以澄清人口和物种范围限制的一般概念。更广泛的影响：N. scabrosus可能是节肢动物基因组比较分析的新资源。 这项研究将为扩大PI，智利研究人员和学生之间的互动提供机会。 一名研究生和一名本科生（资金来自学生研究项目，特别是URM，在U。格鲁吉亚）将参加该项目。 这项研究的所有产品将在适当的遗传（NCBI）和生态（KNB）数据库中公开提供。 预计这项工作将提供一个综合分析海洋学和种群遗传学数据的一般模型，以确定一个物种领域的人口模式。 这些方法可能适用于海洋保护区的设计。 从本质上讲，了解维持沿海海洋地理多样性的机制将有助于在遗传和物种层面管理这一生态系统及其多样性。

Intellectual Merits: Despite great analytical advances for inferring gene flow among marine populations, it is still difficult to identify the populations or mechanisms that maintain spatial variation in demography or connectivity in species with planktonic larvae. How novel diversity is retained in what appear to be well-mixed oceanic systems is poorly understood, particularly the balances between selection and dispersal that influence patterns of genetic variation in these species. This research explores effects of asymmetric dispersal on marine diversity, in general, and on the barnacle Notochthamalus scabrosus along the Chilean coast, in particular. Essentially, the study focuses on how currents influence geogeographic and phylogeograhic patterns of benthic invertebrates with planktonic larvae. In this region, there is a genetic cline of this species that may represent performance-based differences between two distinct lineages of the barnacle, and a transition in nearshore oceanography and intertidal ecology. The mechanisms that allow the cline to persist in the face of larval dispersal will be tested quantitatively. The research would improve the spatial, temporal, and genomic characterization of the cline in N. scabrosus, examine potential selection gradients, and compare indirect estimators of asymmetric gene flow with environmental isolation models that link physical oceanography and phylogeography. The study would be the first empirical exploration of predictions made by recent biogeographic and population-genetic models, developed by the PIs, of the conditions necessary for genetic structure to persist in the coastal ocean. The originality of this project is that instead of relying solely on phylogeographic inference to predict connectivity of populations under various untested assumptions, a combination of physical and biological data would be used to identify the specific mechanisms that maintain coastal diversity. This study would link the dynamics maintaining the N. scabrosus cline to patterns in other marine species actively studied by colleagues in Chile, and would help validate current modeling efforts of larval dispersal along that coast. Moreover, working with Chilean colleagues would be efficient for obtaining and analyzing data needed for this research. The focus on the Chilean coast has a number of benefits, including its intriguing similarity to the well-studied Oregon and California coasts, potentially allowing for generalizations from the results of this work. Most importantly, this work would push source-sink dynamics from the theoretical literature into basic research of how demographic patterns are distributed and maintained across a species' range, with implications for understanding the structure and dynamics of range limits themselves. The work would identify likely source populations along the Chilean coast based on demographic and gene flow analysis, in concert with oceanographic characteristics, and provide a framework transferable to similar efforts along any coast (e.g., Pacific coast of the US), towards clarifying general concepts of population and species range limits. Broader Impacts: Transcriptome data for N. scabrosus would be a new resource for comparative analysis of arthropod genomes. This research would provide opportunities for expanding interactions between the PIs, Chilean researchers and students. One graduate and one undergraduate student (funding leveraged from research programs for students, particularly URM, at U. Georgia) would participate in the project. All products of this research would be made publicly available in appropriate genetic (NCBI) and ecological (KNB) databases. The work is expected to provide a general model for combined analysis of oceanographic and population-genetic data to identify demographic patterns across a species' domain. These methods are likely to be applicable to marine reserve design. Essentially, understanding the mechanisms that maintain phylogeographic diversity in the coastal ocean would help efforts to manage this ecosystem and its diversity at the genetic and species levels.