title: Patterns of selection and allele diversity of class I and class II major histocompatibility loci across the species range of sockeye salmon (Oncorhynchus nerka).
abstract: The major histocompatibility complex (MHC), an important component of the vertebrate immune system, provides an important suite of genes to examine the role of genetic diversity at non-neutral loci for population persistence. We contrasted patterns of diversity at the two classical MHC loci in sockeye salmon (Oncorhynchus nerka), MHC class I (UBA) and MHC class II (DAB), and neutral microsatellite loci across 70 populations spanning the species range from Washington State to Japan. There was no correlation in allelic richness or heterozygosity between MHC loci or between MHC loci and microsatellites. The two unlinked MHC loci may be responding to different selective pressures; the distribution of FST values for the two loci was uncorrelated, and evidence for both balancing and directional selection on alleles and lineages of DAB and UBA was observed in populations throughout the species range but rarely on both loci within a population. These results suggest that fluctuating selection has resulted in the divergence of MHC loci in contemporary populations.
authors.affiliation: Fisheries and Oceans Canada, Pacific Biological Station, 3190 Hammond Bay Rd, Nanaimo, BC, V9T 6N7, Canada.
authors.forename: Erin K
authors.initials: EK
authors.lastname: McClelland
authors.forename: Tobi J
authors.initials: TJ
authors.lastname: Ming
authors.forename: Amy
authors.initials: A
authors.lastname: Tabata
authors.forename: Karia H
authors.initials: KH
authors.lastname: Kaukinen
authors.forename: Terry D
authors.initials: TD
authors.lastname: Beacham
authors.forename: Ruth E
authors.initials: RE
authors.lastname: Withler
authors.forename: Kristina M
authors.initials: KM
authors.lastname: Miller
mesh_terms: D000413:Alaska; D000483:Alleles; D000818:Animals; D001955:British Columbia; D005787:Gene Frequency; D005805:Genes, MHC Class I; D005802:Genes, MHC Class II; D056426:Genetic Loci; D014644:Genetic Variation; D005828:Genetics, Population; D007564:Japan; D018895:Microsatellite Repeats; D012474:Salmon / Q000235:genetics*; D012641:Selection, Genetic; D014861:Washington
keywords: balancing selection; directional selection; heterozygosity; major histocompatibility complex