Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 8954
Title: Evidence for interannual variation in genetic structure of Dungeness crab (Cancer magister) along the California Current System
Author: Tyler M. Jackson, G. Curtis Roegner, Kathleen g. OMalley
Publication Year: 2018
Journal: Molecular Ecology
Volume: 27
Pages: 352-368
DOI: doi: 10.1111/mec.14443

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 interannual 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 sites had significant evidence of relatedness.
Based on these findings, we propose that interannual variation in the physical
oceanographic conditions of the CCS influences larval recruitment and thus gene
flow, contributing to interannual 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, although geographically limited dispersal results in an ephemeral signal
of IBD. Furthermore, our findings demonstrate that populations of marine organisms
may be susceptible to temporal changes in population genetic structure over short
time periods; thus, interannual variability in population genetic measures should be

Theme: Ecosystem approach to improve management of marine resources
Foci: Provide scientific support for the implementation of ecosystem-based management