A steep genetic cline in yellowtail rockfish, Sebastes flavidus, suggests regional isolation across the Cape Mendocino faunal break

As with all Sebastes species, yellowtail rockfish (S. flavidus) produce larvae with an extended pelagic juvenile phase that can be advected in coastal currents. While dispersal potential is high, previous research on population genetic characteristics of Sebastes species indicates that apparent realized dispersal can be much lower and can exhibit complex patterns of genetic structure. We assayed 812 bp of the mitochondrial cytochrome b gene and six microsatellite loci in similar to 1000 yellowtail rockfish collected from 21 sites that span the species range from southern California to southeastern Alaska. An abrupt genetic cline near Cape Mendocino, California, splits the range into a northern and southern stock, and is highly concordant between our mitochondrial (F-CT = 0.32, p << 0.001) and microsatellite (F-CT = 0.02, p << 0.001) datasets. We show that this pattern may be due to a combination of physical (oceanographic or other barriers to larval dispersal), biological (habitat differences), and historical events. This study, and both intra-and inter-specific evidence from other marine species suggests Cape Mendocino demarcates two regions experiencing divergent evolutionary trajectories, and should be considered in management strategies.