Collaborative Research: NSFGEO-NERC: Using population genetic models to resolve and predict dispersal kernels of marine larvae

大多数海洋生物通过产生数百万个微小的浮游幼虫来繁殖，这些幼虫被洋流分散在不同的距离和方向。特定种群幼虫的空间分布，也称为扩散核，是基本了解海洋生态和进化以及管理和养护海洋资源的一个重要参数。幼虫扩散核通常使用计算机模型来研究，该模型模拟了海洋环流模型中幼虫的扩散。然而，有很少的测量海洋幼虫扩散，以评估这些计算机模型，由于成本和不可行的目前的遗传标记方法。该项目使用距离隔离（IbD）群体模型，该项目团队已经证明该模型与遗传标记方法具有相似的结果，但成本仅为一小部分。分散的内核被认为是由两个物种的特征，如花时间作为幼虫，以及环境，通过幼虫分散。为了区分物种特征和区域海景的影响，该团队正在利用南太平洋的独特环境，在那里，众多孤立的群岛各自独立地复制了该团队正在研究的扩散过程。六个珊瑚礁鱼类物种在10个地点在每个新喀里多尼亚，瓦努阿图和斐济群岛的海景进行采样，然后使用IBD估计的扩散内核选择一组计算机模型，和模型模拟二十年的海洋学数据（许多代的鱼）和物种特征的选择。这项研究的结果正被用来改进每个群岛海洋保护区网络的设计，以考虑到幼虫扩散随时间的变化。这项研究建立在印度-太平洋网络多样性（DIPnet）的努力基础上，该网络由该项目的主要研究人员和高级人员创建，旨在促进对印度-太平洋巨大生物多样性的生态和演变的合作研究。该项目还为博士后科学家、研究生和本科生提供培训，并支持为当地决策者和学生举办能力建设讲习班。了解扩散事件（扩散核）的空间分布是海洋生态学的一个基本目标，对于预测种群动态和进化结果至关重要。然而，预测社区间扩散结果的一般原则仍然难以捉摸。该项目小组正在开发首个数据同化的幼虫扩散生物物理模型，方法是：1）应用距离隔离（IbD）理论来估计在三个隔离的南太平洋群岛共同采样和RAD-seq基因分型的六种珊瑚鱼物种的平均亲子距离（σIbD），每个群岛都用相对连续的珊瑚礁系统复制IbD过程，2）使用σIbD的经验估计来约束幼虫扩散的生物物理模型，这些模型在20年的高分辨率水动力模型上迭代，以检验关于物种特征和海景特征在形成幼虫扩散核中的相对作用的假设，和3）开发一种新的保护组合方法来设计管理区域网络，以捕获多代幼虫扩散的时间变化，该奖项反映了NSF的法定使命，并通过利用基金会的知识价值和更广泛的影响进行评估，被认为值得支持审查标准。

Most marine organisms reproduce by creating millions of tiny planktonic larvae which are dispersed across a variety of distances and directions by ocean currents. The spatial distribution of larvae from a given population, also known as the dispersal kernel, is an important parameter both for basic understanding of marine ecology and evolution, as well as for management and conservation of marine resources. Larval dispersal kernels are often studied using computer models which simulate the dispersal of larvae within ocean circulation models. However, there are very few measurements of marine larval dispersal with which to evaluate these computer models, due the cost and infeasibility of current genetic tagging methods. This project uses isolation by distance (IbD) population models, which the project team has shown gives similar results to genetic tagging methods, but at a fraction of the cost. Dispersal kernels are thought to be shaped by both species traits, such as the amount of time spent as planktonic larvae, as well as the environment through which the larvae disperse. To tease apart the effects of species traits and regional seascapes, the team is taking advantage of the unique setting of the South Pacific, where the numerous isolated archipelagos each independently replicate the dispersal process the team is studying. Six reef-fish species at ten locations in each of the New Caledonia, Vanuatu, and Fijian archipelagic seascapes are being sampled, IbD estimates of dispersal kernels are then used to select a set of computer models, and the models are simulated across twenty years of oceanographic data (many generations of fish) and a selection of species traits. The results of this research are being used to improve the design of networks of marine protected areas in each of the archipelagos in a way that accounts for variability in larval dispersal over time. This research builds on the efforts of the Diversity of the Indo-Pacific Network (DIPnet), created by the project’s principal investigators and senior personnel to promote collaborative research on the ecology and evolution of the immense biodiversity of the Indo-Pacific. The project also provides training for postdoctoral scientists, graduate and undergraduate students, and supports capacity building workshops for local policymakers and students.Populations of most marine species are functionally, demographically, and genetically connected by planktonic dispersal of tiny larvae. Understanding the spatial distribution of dispersal events (the dispersal kernel) is a fundamental goal of marine ecology and is critical to predicting population dynamics and evolutionary outcomes. Yet, general principles for predicting dispersal outcomes across communities remain elusive. The project team is developing the first-ever data-assimilated biophysical models of larval dispersal by: 1) applying isolation-by-distance (IbD) theory to estimate mean parent-offspring distance (σIbD) for six reef fish species co-sampled and RAD-seq genotyped at three isolated South Pacific archipelagos that each replicate the IbD process with relatively continuous reef systems, 2) using empirical estimates of σIbD to constrain biophysical models of larval dispersal, which are iterated over twenty years of high-resolution hydrodynamic models, to test hypotheses about the relative role of species traits and seascape characteristics in shaping larval dispersal kernels, and 3) developing a new conservation portfolio approach to design managed area networks that capture temporal variability in larval dispersal over many generations, and engaging with local stakeholders in each archipelago to implement this approach.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.