title: Varying disease-mediated selection at different life-history stages of Atlantic salmon in fresh water.
abstract: Laboratory studies on associations between disease resistance and susceptibility and major histocompatibility (MH) genes in Atlantic salmon Salmo salar have shown the importance of immunogenetics in understanding the capacity of populations to fight specific diseases. However, the occurrence and virulence of pathogens may vary spatially and temporally in the wild, making it more complicated to predict the overall effect that MH genes exert on fitness of natural populations and over several life-history stages. Here we show that MH variability is a significant determinant of salmon survival in fresh water, by comparing observed and expected genotype frequencies at MH and control microsatellite loci at parr and migrant stages in the wild. We found that additive allelic effects at immunogenetic loci were more likely to determine survival than dominance deviation, and that selection on certain MH alleles varied with life stage, possibly owing to varying pathogen prevalence and/or virulence over time. Our results highlight the importance of preserving genetic diversity (particularly at MH loci) in wild populations, so that they have the best chance of adapting to new and increased disease challenges as a result of projected climate warming and increasing aquaculture.
authors.affiliation: Marine Institute Newport, Co Mayo, Ireland.
authors.forename: Elvira
authors.initials: E
authors.lastname: de Eyto
authors.affiliation: Department of Zoology, Ecology and Plant Science/Aquaculture and Fisheries Development Centre, University College Cork Distillery Fields, North Mall, Cork, Ireland.
authors.forename: Philip
authors.initials: P
authors.lastname: McGinnity
authors.affiliation: Department of Biology, Norwegian University of Science and Technology Trondheim, Norway.
authors.forename: Jisca
authors.initials: J
authors.lastname: Huisman
authors.affiliation: Department of Zoology, Ecology and Plant Science/Aquaculture and Fisheries Development Centre, University College Cork Distillery Fields, North Mall, Cork, Ireland.
authors.forename: Jamie
authors.initials: J
authors.lastname: Coughlan
authors.affiliation: Aberystwyth University, Institute of Biological, Environmental & Rural Sciences Aberystwyth, UK.
authors.forename: Sofia
authors.initials: S
authors.lastname: Consuegra
authors.affiliation: Marine Institute Newport, Co Mayo, Ireland.
authors.forename: Killian
authors.initials: K
authors.lastname: Farrell
authors.affiliation: Department of Zoology, Ecology and Plant Science/Aquaculture and Fisheries Development Centre, University College Cork Distillery Fields, North Mall, Cork, Ireland.
authors.forename: Ciar
authors.initials: C
authors.lastname: O'Toole
authors.affiliation: Department of Mathematical Sciences, Norwegian University of Science and Technology Trondheim, Norway.
authors.forename: Jarle
authors.initials: J
authors.lastname: Tufto
authors.affiliation: Department of Animal Sciences, Wageningen University Wageningen, the Netherlands.
authors.forename: Hendrik-Jan
authors.initials: HJ
authors.lastname: Megens
authors.affiliation: Institute of Zoology, Zoological Society of London Regent's Park, London, UK.
authors.forename: William
authors.initials: W
authors.lastname: Jordan
authors.affiliation: Department of Zoology, Ecology and Plant Science/Aquaculture and Fisheries Development Centre, University College Cork Distillery Fields, North Mall, Cork, Ireland.
authors.forename: Tom
authors.initials: T
authors.lastname: Cross
authors.affiliation: Scottish Fish Immunology Research Centre, University of Aberdeen Zoology Building, Tillydrone Avenue, Aberdeen, UK.
authors.forename: Rene J M
authors.initials: RJ
authors.lastname: Stet
keywords: Atlantic salmon; Salmo salar; freshwater life stages; major histocompatibility; natural selection