Using multiple natural tags provides evidence for extensive larval dispersal across space and through time in summer flounder: Hoey et al. paper out in Molecular Ecology!

Jennifer Hoey, a Pinsky Lab PhD candidate, and a team of collaborators published a paper exploring larval flounder dispersal last week in Molecular Ecology. They used both SNP genotypes and otolith core microchemistry from 411 archived summer flounder (Paralichthys dentatus) samples collected between 1989 and 2012 at five locations along the U.S. east coast to reconstruct dispersal patterns over time. While neither genotypes nor otolith microchemistry alone were sufficient to identify the source of larval fish, they used otolith microchemistry to identify clusters of larvae that originated in the same location, which allowed them to make genetic assignments of clusters with more confidence. They found that most larvae likely originated near Cape Hatteras, a biogeographic break, and that larvae were transported both north and south of the break. Larval sources did not move north over time, despite the northward shift of adult populations over the same time period. Their novel, multi-tag approach, demonstrates that summer flounder dispersal is widespread throughout their range, on both intra‐ and inter‐generational timescales, and may be a particularly important process for synchronizing population dynamics and maintaining genetic diversity during an era of rapid environmental change. Broadly, their results reveal the value of archived collections and of combining multiple natural tags to understand the magnitude and directionality of dispersal in species with extensive gene flow.