Spatial Autocorrelation Reveals Fine-Scale Genetic Structure and Sex-Biased Dispersal in Two Rockfish (Sebastes) Life-History Types

Dispersal is an important life-history trait that greatly influences spatial genetic structure among marine populations, which has significant consequences to fisheries economy. Dispersal strategies may also vary between sexes; females can be more philopatric than males if they provide parental investment to the young. Here we studied dispersal patterns among canary (Sebastes pinniger) and darkblotched rockfish (Sebastes crameri), two rockfishes that are widely distributed off the west coast of North America and face considerable conservation risks, but differ in life history traits. Using multilocus genotype data (seven microsatellite loci per species) from 1,998 individuals (canary; n = 470; darkblotched n =  1528), our results provide evidence for significant spatial autocorrelation (r) in both species, even though genetic structure for canary was higher and occurred at finer scales (0-19 km) than darkblotched (0-174 km). Differences in dispersal evident between sexes among canary (female r= 0.027, male r= 0.015) suggests that females are more philopatric than males, but not among darkblotched populations (female r = 0.003; male r= 0.003). Overall, our findings demonstrate that fine-scale genetic structure in many rockfish species may go undetected with other methods, and that male-biased dispersal implies a possible trade-off between investing energy in reproduction or dispersion.