Data from: Evidence for interannual variation in genetic structure of Dungeness crab (Cancer magister) along the California Current System

Using a combination of population- and individual-based analytical
approaches, we provide a comprehensive examination of genetic connectivity
of Dungeness crab (Cancer magister) along ~1,200 km of the California
Current System (CCS). We sampled individuals at 33 sites in 2012 to
establish a baseline of genetic diversity and hierarchal population
genetic structure, and then assessed inter-annual variability in our
estimates by sampling again in 2014. Genetic diversity showed little
variation among sites or across years. In 2012, we observed weak genetic
differentiation among sites (FST range = -0.005 – 0.014) following a
pattern of isolation by distance (IBD), and significantly high relatedness
among individuals within nine sampling sites. In 2014, pairwise FST
estimates were lower (FST range = -0.014 – 0.007), there was no spatial
autocorrelation, and fewer sights had significant evidence of relatedness.
Based on these findings, we propose that inter-annual variation in the
physical oceanographic conditions of the CCS influence larval recruitment
and thus gene flow, contributing to inter-annual variation in population
genetic structure. Estimates of effective population size (Ne) were large
in both 2012 and 2014. Together, our results suggest that Dungeness crab
in the CCS may constitute a single evolutionary population, though
geographically limited dispersal results in an ephemeral signal of
isolation by distance. Furthermore, our findings demonstrate that
populations of marine organisms may be susceptible to temporal changes in
population genetic structure over short time periods, thus inter-annual
variability in population genetic measures should be considered.