Biogeographical genetic variation of the Dungeness crab ( Cancer magister)

The genetic structure and phylogeography of Dungeness crab ( Cancer magister) populations from Alaska, Washington, Oregon, and California were assessed by sequencing the mitochondrial Cytochrome c Oxidase subunit I (COI) and nuclear Elongation Factor alpha subunit (EF1alpha) genes. High COI haplotype diversity (350 haplotypes among 846 crabs, h = 0.940), and high nucleotide diversity (0.01435) was observed. The incidence of universal COI and EF1alpha haplotypes and low differentiation between populations (FST = 0.00655-0.17956, GST = 0.00237-0.01722) revealed an absence of population structure and suggest a high level of gene flow over the range of C. magister. This finding is supported by MANTEL and AIS tests (comparing geographic distance to genetic distance), which also show little geographic structure. Coalescence analysis indicates a genetic bottleneck occurred approximately 78,000-146,000 YBP. High dispersal capability and high genetic diversity suggest that a few, strategically placed marine reserves along the crabs' range might maintain the evolutionary potential of this species.