| The population genetic structure and phylogeography of marine invertebrates with high larval dispersal capacity typically reflects both contemporary and historical processes. I sampled 346 individuals from seven populations of Pachygrapsus crassipes Randall (lined shore crab) along the northeastern Pacific Coast and Korea during summer 2003. Amplification of the mitochondrial COI gene revealed significant genetic structuring at Point Conception, CA. This is likely the result of oceanographic circulation patterns, leading to the asymmetrical migration of haplotypes. Low levels of genetic structuring among eastern Pacific populations is probably due to high contemporary gene flow and recent common ancestry of haplotypes. The population history of this species is characterized by northwards range expansions, which are congruent with Late Pleistocene glacial cycles. Significant genetic differentiation was detected between eastern and western Pacific populations, indicating transpacific gene flow is restricted. Time of divergence between the two lineages occurred between 0.8 and 1.2 million years ago. |
