Data from: On-shelf larval retention limits population connectivity in a coastal broadcast spawner

Broadcast-spawning marine organisms with long pelagic larval duration are
often expected to be genetically homogeneous throughout their ranges. When
genetic structure is found in such taxa, it may be in the form of chaotic
genetic patchiness: i.e. patterns that might seem independent of any
underlying environmental variation. The joint analysis of population
genetic data and marine environmental data can elucidate factors driving
such spatial genetic diversity patterns. Using meso-scale sampling (at a
scale of 10s to 100s of km), microsatellite data and advection
connectivity simulations, we studied the effect of temperate southern
Australian ocean circulation on the genetic structure of the snail Nerita
atramentosa. This species has a long pelagic larval duration and is
represented as a single metapopulation throughout its ~3000 km range, but
even so, we found that its dispersal potential is lower than expected.
Connectivity simulations indicate that this is a result of the larvae that
remain on the continental shelf (where currents are erratic and often
shoreward) returning to the coast in much larger numbers than larvae that
become entrained in the region’s shelf-edge boundary currents. Our study
contributes to the growing evidence that departures from the expectations
of panmixia along continuous and environmentally homogeneous coastlines
are not limited to low-dispersal species, and it identifies on-shelf
larval retention as an important factor limiting dispersal.