Temporal recruitment patterns and gene flow in kelp rockfish (Sebastes atrovirens)

Abstract

Pelagic dispersal of marine organisms provides abundant opportunity for gene flow and presumably inhibits population genetic divergence. However, ephemeral, fine-scale, temporal and spatial genetic heterogeneity is frequently observed in settled propagules of marine species that otherwise exhibit broad-scale genetic homogeneity. A large variance in reproductive success is one explanation for this phenomenon. Here, genetic analyses of 16 microsatellite loci are used to examine temporal patterns of variation in young-of-year kelp rockfish (Sebastes atrovirens) recruiting to nearshore habitat in Monterey Bay, California, USA. Population structure of adults from central California is also evaluated to determine if spatial structure exists and might potentially contribute to recruitment patterns. Genetic homogeneity was found among 414 young-of-year sampled throughout the entire 1998 recruitment season. No substantial adult population structure was found among seven populations spanning 800 km of coastline that includes the Point Conception marine biogeographic boundary. Comparison of young-of-year and adult samples revealed no genetic differentiation and no measurable reduction in genetic variation of offspring, indicating little variance in reproductive success and no reduction in effective population size for this year class. Simulation analyses determined that the data set was sufficiently powerful to detect both slight population structure among adults and a small reduction in effective number of breeders contributing to this year class. The findings of high gene flow and low genetic drift have important implications for fisheries management and conservation efforts.

Circumpolar genetic population structure of capelin Mallotus villosus

“…Atlantic cod Gadus morhua (Nielsen et al 2001). Our estimates, however, correspond well with recent reports on marine fishes that have a high potential for dispersal (Gilbert-Horvath et al 2006, O'Leary et al 2007). None of these authors suggests implicitly that the failure to correctly assign individuals to their native population arises from the biological dynamics of these species.…”

Population genetic structure of wild and hatchery black rockfish Sebastes inermis in Korea, assessed using cross-species microsatellite markers

“…We found no differentiation among wild S. inermis populations, despite different sea basin origins. The lack of significant genetic differentiation between the wild populations we sampled is consistent with the lack of genetic divergence found in wild S. inermis from mtDNA sequence variability studies (Higuchi and Kato, 2002), as well as that of other Sebastes species (Rocha-Olivares et al, 2003;Gilbert-Horvath et al, 2006). This could result from sufficient gene flow during the black rockfish pelagic phase.…”

Multiple paternity and maintenance of genetic diversity in the live-bearing rockfishes Sebastes spp.

“…Interestingly, Gilbert-Horvath et al (2006) found no evidence for genetic heterogeneity between individual recruitment pulses of young-of-theyear and adult populations of kelp rockfish Sebastes atrovirens, a species shown in the present study and that of Sogard et al (2008) to practice multiple paternity. The authors suggest this as evidence that sweepstakes recruitment does not occur in this species; however, this lack of heterogeneity could also be due to the increased genetic diversity of multiply sired broods.…”