Nereus Program Principal Investigator Malin Pinsky (Rutgers University) is a co-author on a study recently published in Molecular Ecology. The authors investigate larval dispersal patterns of the summer flounder (Paralichthys dentatus) along the U.S. East Coast using different natural genetic and microchemical (otolith) analyses and natural history records, finding that most larvae disperse in different directions originating from a region near Cape Hatteras, North Carolina. They showed that by combining the genetic and microchemical approaches, current estimated larval dispersal is greatly improved. Additionally, when natural history biological collections are used, one can deduce ecological and evolutionary processes. They find that, by combining all three approaches, there results a deeper level of understanding in the summer flounders’ dispersal over space and time. You can read the full abstract below.

Abstract

Dispersal sets the fundamental scales of ecological and evolutionary dynamics and has important implications for population persistence. Patterns of marine dispersal remain poorly understood, partly because dispersal may vary through time and often homogenizes allele frequencies. However, combining multiple types of natural tags can provide more precise dispersal estimates, and biological collections can help to reconstruct dispersal patterns through time. We used single nucleotide polymorphism genotypes and otolith core microchemistry from archived collections of larval summer flounder (Paralichthys dentatus, n = 411) captured between 1989 and 2012 at five locations along the US East coast to reconstruct dispersal patterns through time. Neither genotypes nor otolith microchemistry alone were sufficient to identify the source of larval fish. However, microchemistry identified clusters of larvae (n = 3–33 larvae per cluster) that originated in the same location, and genetic assignment of clusters could be made with substantially more confidence. We found that most larvae probably originated near a biogeographical break (Cape Hatteras) and that larvae were transported in both directions across this break. Larval sources did not shift north through time, despite the northward shift of adult populations in recent decades. Our novel approach demonstrates that summer flounder dispersal is widespread throughout their range, on both intra- and intergenerational timescales, and may be a particularly important process for synchronizing population dynamics and maintaining genetic diversity during an era of rapid environmental change. Broadly, our 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.

Reference

Hoey, J. A., Fodrie, F. J., Walker, Q. A., Hilton, E. J., Kellison, G. T., Targett, T. E., Taylor, J.C., Able, K.W. & Pinsky, M. L. (2020). Using multiple natural tags provides evidence for extensive larval dispersal across space and through time in summer flounder. Molecular Ecology. doi: 10.1111/MEC.15414