Influence of habitat discontinuity, geographical distance, and oceanography on fine‐scale population genetic structure of copper rockfish (Sebastes caurinus)

Abstract

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.

Speciation along a depth gradient in a marine adaptive radiation

“…While rockfishes have a pelagic larval phase and are capable of long-distance dispersal, local recruitment of larvae and site fidelity of adults can permit genetic structure within species (e.g. [21]). Thus, isolation by physical distance might result in allopatric divergence between northern and southern populations [19].…”

Phylogeny and phylogeography of Atlantic oyster species: evolutionary history, limited genetic connectivity and isolation by distance

“…Palumbi 2003, Johansson et al 2008, including studies of Crassostrea species (Hedgecock & Okazaki 1984, Hare & Avise 1998, Xiao et al 2010. Population genetic studies have unveiled patterns of isolation by distance among oyster populations (Launey et al 2002, Rose et al 2006, Xiao et al 2010, and are of great interest not only when addressing evolutionary and ecological processes but also as a basis for management and conservation of commercially important marine species.…”

Spatial and temporal population genetics at deep-sea hydrothermal vents along the East Pacific Rise and Galapagos Rift

“…Exact tests of genic and genotypic differentiation, variation along the first principal component axis of a PCA, individual partitioning in STRUCTURE analysis, and multi-locus estimates of F ST and R ST revealed significant differences between the two ridge population assemblages. Small (less than 3% F ST ) but significant genetic distance between Riftia populations on the EPR and GAR may indicate that long-distance larvae originating from one ridge may occasionally colonize hydrothermal vent sites along the other ridge, but the preponderance of evidence here suggests that populations on each ridge system are primarily self-seeding on a mesoscale level (as in Johansson et al 2008) and that gene flow between them is a relict of historic processes.…”