Collaborative Research: RUI: Combined spatial and temporal analyses of population connectivity during a northern range expansion

幼小的海鱼和贝类从哪里来？该项目旨在提高我们对沿海海洋种群在空间和时间上如何联系的理解。沿海种群的补充是通过微小幼虫的到来，这些幼虫在偏远地点产卵后，在公海上分散了几周到几个月。海洋鱼类和贝类幼体的长传播期和不同的洋流共同导致了远近种群之间复杂的“联系”模式。确定这些连接模式是海洋科学的基础，对有效的渔业管理和养护至关重要，但它仍然是海洋生态的一个尚未解决的组成部分。这种被研究的物种目前正在扩大其在美国西海岸的生物地理范围。通过对整个物种范围内的个体进行遗传分析，包括在实验室中从整个物种历史范围和扩展范围内收集的实验杂交个体在实验室中繁殖的后代，某些基因可以用来区分沿海地区的种群。该团队利用这些地理信息基因的统计能力，将在野外收集的数千只幼崽分配给繁殖它们的来源种群(跨越物种范围，历时数年)。然后，该团队量化了多年的连通性模式，并测试了关于人口连通性的空间尺度、时间变异性、生物地理模式和生物物理驱动因素的基本假设。该项目在分子生态学和海洋科学方面培训了大约24名美国大学生，并在授予博士学位的大学和非授予博士学位的大学之间建立了智力联系。该项目还支持进一步开发K-12教育项目，使用潜水和录像技术向小学生传授下一代科学标准，并为他们在科学、技术、工程和数学领域的职业生涯进行培训。利用海带森林腹足类和渔业物种(Kellet‘s Spink，Kelletia Kelletii)，该项目将全基因组限制酶切点相关DNA(RAD)基因座与从该物种历史和扩展范围的共同花园实验室杂交中识别的转录基因座结合起来，以确定具有地理信息的基因座，从而最大限度地提高个体分配测试的能力。利用这些基因座的综合力量，将大约3000个招募样本遗传分配给20个假定的源种群，使该团队能够构建三个独立年份的连通性矩阵，并测试海洋生态学中的一些最基本的问题，包括：1)海洋种群是开放的还是封闭的，规模是多大？2)基因流动的进化模式在多大程度上代表了单代或多代的连通性事件？以及，3)人口连通性在空间上的异质性和时间上的变量有多大？一年的连通性数据能预测下一年的情况吗？此外，通过关注具有共同生活史特征的范围扩大的物种，该团队解决了一些具有广泛适用性和重大生态和社会影响的问题：4)招募后人口和进化过程对种群连通性的影响有多大？5)历史种群和扩大范围的种群之间的联系有多好？而且，与气候变化特别相关的是，厄尔尼诺海洋条件是否推动了这种沿海海洋生物向极地范围的扩大？预计本世纪厄尔尼诺现象的频率和强度将会增加。通过将普通花园实验杂交与野外样本的基因组RAD分析相结合来确定信息量最大的转录基因座，该项目旨在准确和精确地量化种群规模较大的高基因流动物种的海洋种群连通性。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。

Where do young marine fish and shellfish come from? This project aims to improve our understanding of how coastal marine populations are connected in space and time. Coastal populations are replenished through the arrival of minuscule larvae that have been dispersed for weeks to months in the open ocean after spawning at remote sites. The combination of the long dispersal period of marine fish and shellfish larvae and the varying ocean currents results in complex patterns of "connectivity" among populations near and far. Identifying these patterns of connectivity is fundamental to marine science and critical for effective fisheries management and conservation, yet it remains an unresolved component of marine ecology. The study species is currently expanding its biogeographic range up the U.S. west coast. By genetically analyzing individuals from across the species' range, including offspring spawned in the laboratory by experimentally-crossed individuals collected in the field from throughout the species historical and expanded range, certain genes can serve to differentiate populations along the coast. The team leverages the statistical power of these geographically-informative genes to assign thousands of young collected in the field to the source populations that spawned them (across the species' range and over multiple years). The team then quantifies patterns of connectivity over multiple years, and tests fundamental hypotheses on the spatial scale, temporal variability, biogeographic patterns, and biophysical drivers of population connectivity. The project trains approximately two dozen U.S. university students in molecular ecology and marine science, as well as creating intellectual linkages among Ph.D.-granting and non-Ph.D.-granting universities. The project also supports further development of a K-12 education program that uses SCUBA diving and videography to teach elementary school students Next Generation Science Standards and train them for careers in science, technology, engineering and mathematics. Using a kelp forest gastropod and fisheries species (Kellet's whelk, Kelletia kelletii), this project combines genome-wide Restriction site Associated DNA (RAD) loci with transcriptomic loci identified from common-garden laboratory crosses of individuals from the species' historical and expanded range to identify geographically-informative loci that maximize power for individual assignment testing. Leveraging the combined power of these loci, genetic assignment of approximately three thousand recruit samples to 20 putative source populations allows the team to construct three independent years of connectivity matrices and test some of the most fundamental questions in marine ecology, including: 1) Are marine populations open or closed and at what scales? 2) To what degree is the evolutionary pattern of gene flow represented by single versus multiple generations of connectivity events? And, 3) How spatially heterogeneous and temporally variable is population connectivity? Can one year of connectivity data predict anything about the next? Additionally, by focusing on a range-expanding species with common life history traits, the team addresses a number of questions with broad applicability and significant ecological and societal implications: 4) How much is population connectivity influenced by post-recruitment demographic and evolutionary processes? 5) How well-connected are historic- and expanded-range populations? And, of particular relevance to climate change, 6) Are El Nino oceanographic conditions, which are predicted to increase in frequency and intensity this century, driving the poleward range expansion of this coastal marine species? By coupling common-garden experimental crosses to identify maximally-informative transcriptomic loci with genomic RAD analysis of field samples, this project aims to accurately and precisely quantify marine population connectivity in high gene flow species with large population sizes.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.