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

NSF Award Abstract: 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 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 IbD 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. NSFGEO-NERC Collaboration: This is a project jointly funded by the National Science Foundation’s Directorate for Geosciences (NSF/GEO) and the National Environment Research Council (NERC) of the United Kingdom (UK).  Maria ​Beger (Leeds University) is the Principal Investigator of the NERC award.  The award number will be added to this project page once it is available.