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创造数百万只微小的浮游幼虫进行繁殖，这些幼虫被洋流分散在不同的距离和方向上。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保护海洋资源的重要参数。通常使用计算机模型来研究幼虫的扩散核，这些模型在海洋环流模型中模拟幼虫的扩散。然而，由于目前遗传标记方法的成本和不可行，用于评估这些计算机模型的海洋幼虫扩散的测量很少。这个项目使用了按距离隔离(IBD)种群模型，项目团队已经展示了这种模型给出了类似于基因标签方法的结果，但成本只有它的一小部分。扩散核被认为是由两个物种特征决定的，例如作为浮游幼虫的时间长短，以及幼虫散布的环境。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，众多孤立的群岛每个都独立地复制了该团队正在研究的扩散过程。在新喀里多尼亚、瓦努阿图和斐济群岛的每个海景的10个地点采集了6种珊瑚鱼，然后使用IBD对扩散核心的估计来选择一套计算机模型，并对这些模型进行了20年的海洋数据(许多代鱼)和一系列物种特征的模拟。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，以考虑到幼虫随时间传播的可变性。这项研究建立在印度-太平洋多样性网络(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进化的合作研究。该项目还为博士后科学家、研究生和本科生提供培训，并支持为当地政策制定者和学生举办能力建设讲习班。大多数海洋物种的种群在功能上、人口统计学上和基因上都与微小幼虫的浮游扩散有关。了解扩散事件(扩散的核心)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，预测跨社区传播结果的一般原则仍然难以捉摸。该项目团队正在开发首个数据同化的幼虫传播生物物理模型，方法是：1)应用距离隔离(Ibd)理论估计在三个孤立的南太平洋群岛进行共同采样和σ-seq基因分型的六种珊瑚礁鱼类的平均亲子距离(rad-seq)；2)使用σibd的经验估计来约束幼虫传播的生物物理模型，该模型在20年的高分辨率水动力学模型中迭代，以测试关于物种特征和海景特征在形成幼虫传播核心中的相对作用的假设。以及3)开发一种新的保护组合方法来设计受管理的区域网络，以捕捉幼虫在许多世代中传播的时间变异性，并与每个群岛的当地利益相关者合作实施这一方法。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。

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.