Replicate divergence between and within sounds in a marine fish: the copper rockfish (Sebastes caurinus)

The evolution of population structure in marine organisms and its relevance to conservation has recently received increasing attention. We tested the degree of genetic subdivision among ten populations of copper rockfish (Sebastes caurinus) representing paired samples of outer coast and the heads of five replicate sounds on the west coast of Vancouver Island, British Columbia using 17 microsatellite DNA loci. Overall, subdivision (FST) was low (FST = 0.031), but consistently higher between paired coast and head of inlet sites (mean FST = 0.047) compared to among five coast sites (mean FST = -0.001) or among the five head of inlet sites (mean FST = 0.026). Heterozygosity, allelic richness, and estimates of effective population size were also consistently lower in head of inlet sites than in coast sites. Bayesian analysis of population structure identified two genetic groups across all samples, a single genetic group amongst only coast samples, two genetic groups amongst head of inlet sam...