Influence of habitat discontinuity, geographical distance, and oceanography on fine-scale population genetic structure of copper rockfish (Sebastes caurinus).
The copper rockfish is a benthic, nonmigratory, temperate rocky reef marine species with pelagic larvae and juveniles. A previous range-wide study of the population-genetic structure of copper rockfish revealed a pattern consistent with isolation-by-distance. This could arise from an intrinsically limited dispersal capability in the species or from regularly-spaced extrinsic barriers that restrict gene flow (offshore jets that advect larvae offshore and/or habitat patchiness). Tissue samples were collected along the West Coast of the contiguous USA between Neah Bay, WA and San Diego, CA, with dense sampling along Oregon. At the whole-coast scale (approximately 2200 km), significant population subdivision (F(ST) = 0.0042), and a significant correlation between genetic and geographical distance were observed based on 11 microsatellite DNA loci. Population divergence was also significant among Oregon collections (approximately 450 km, F(ST) = 0.001). Hierarchical amova identified a weak but significant 130-km habitat break as a possible barrier to gene flow within Oregon, across which we estimated that dispersal (N(e)m) is half that of the coast-wide average. However, individual-based Bayesian analyses failed to identify more than a single population along the Oregon coast. In addition, no correlation between pairwise population genetic and geographical distances was detected at this scale. The offshore jet at Cape Blanco was not a significant barrier to gene flow in this species. These findings are consistent with low larval dispersal distances calculated in previous studies on this species, support a mesoscale dispersal model, and highlight the importance of continuity of habitat and adult population size in maintaining gene flow.
Johansson
M L
ML
Coastal Oregon Marine Experiment Station, Hatfield Marine Science Center, Oregon State University, 2030 SE Marine Science Drive, Newport, OR 97365, USA. mattias.johansson@oregonstate.edu
Banks
M A
MA
Glunt
K D
KD
Hassel-Finnegan
H M
HM
Buonaccorsi
V P
VP
D000704:Analysis of Variance; D000818:Animals; D002140:California; D017753:Ecosystem; D005399:Fishes / Q000145:classification / Q000235:genetics* / Q000254:growth & development; D014644:Genetic Variation; D005828:Genetics, Population; D005843:Geography; D018895:Microsatellite Repeats / Q000235:genetics; D009791:Oceanography / Q000379:methods*; D009922:Oregon; D010140:Pacific Ocean; D014861:Washington