Population structure of copper rockfish (Sebastes caurinus) reflects postglacial colonization and contemporary patterns of larval dispersal

Abstract

The copper rockfish (Sebastes caurinus) is a benthic, nonmigratory, rocky reef species with pelagic larval and juvenile stages lasting several months. Adults are commonly distributed in temperate coastal waters of the Pacific Ocean from British Columbia to southern California, including the inland waterways of Puget Sound, Washington, a semi-enclosed fjord system of known postglacial origin. Here, we report the distribution of genetic variation at six microsatellite DNA loci from six locations throughout the species' range. Among four coastal samples, significant population subdivision was detected (FST = 0.007), and a significant correlation between genetic and geographic distance was observed. Divergence was large and significant between Puget Sound proper and coastal samples (FST = 0.087). A sample taken only 100 km north of Puget Sound (the Canadian Gulf Islands) was also highly divergent from Puget Sound and coastal samples and was genetically intermediate between the two. The Puget Sound sample also displayed significantly lower allelic diversity and a more substantial presence of private alleles. The patterns of genetic divergence and diversity are most consistent with a historical colonization followed by limited oceanographic exchange among geographically proximate locations.

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

“…In this study, the genetic variation of wild population samples of Korean S. inermis was low relative to that reported in other Sebastes species (Rocha-Olivares et al, 2003;Buonaccorsi et al, 2002Buonaccorsi et al, , 2004, as well as other marine fishery species (DeWoody and Avise, 2000). However, similar genetic variability was reported in S. maliger (Wimberger et al, 1999) and S. thompsoni (Sekino et al, 2001).…”

Microsatellite variation in the Mexican rockfish <i>Sebastes macdonaldi</i>

“…A very close value (mean He = 0.72 in a set of shared loci) was found among 400 grass rockfish S. rastrelliger sampled along the Pacific coasts of Oregon and California (Buonaccorsi et al, unpublished data). Buonaccorsi et al (2002) studied exactly the same loci analysed here (except for Sra7-2) in the copper rockfish Sebastes caurinus finding 0.63 ≤ He ≤ 0.71 in fish sampled throughout its geographic range. Overlapping levels of microsatellite heterozygosity (0.5-0.87) were found at six loci of the Pacific ocean perch Sebastes alutus (Miller et al, 2000).…”

“…In a study that included the same loci used here, except for Sra11-103, Buonaccorsi et al (unpublished data) also found a low and marginally significant partitioning (F ST = 0.0013, p = 0.0497) in the grass rockfish S. rastrelliger distributed continuously along the coasts of California and Oregon. The same loci, however, were all significantly differentiated (overall F ST = 0.036, p < 0.001) among populations of copper rockfish (Buonaccorsi et al, 2002).…”

“…Presumably-isolated populations of Puget Sound copper rockfish S. caurinus were found to be highly divergent from nearby samples taken from the Gulf Islands (F ST = 0.037) and from the Pacific coast (F ST = 0.087) at the same loci studied here. The age of Puget Sound populations cannot be more than 11,500 years, a time at which the sound became marine after being filled with fresh water as the glaciers melted in the area (Buonaccorsi et al, 2002). The degree of genetic partitioning between Gulf of California and Pacific populations of the Mexican rockfish is only one third to one seventh of that amount.…”

“…The degree of genetic partitioning between Gulf of California and Pacific populations of the Mexican rockfish is only one third to one seventh of that amount. The large genetic differentiation observed in the copper rockfish may be partly explained by natural selection (Buonaccorsi et al, 2002), as Pacific and Puget Sound fish may face different selective pressures. However, it is unlikely that all loci would have been equally affected by genetic hitchhiking to a selected locus, and one can also argue that populations of the Gulf of California are subject to a very different physical environment than those in the Pacific (Alvarez-Borrego, 2001;Chen, 1975).…”