1. Natural selection acts on Atlantic salmon major histocompatibility (MH) variability in the wild
- Author
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Sofia Consuegra, Thomas F. Cross, Elvira de Eyto, William C. Jordan, Hendrik-Jan Megens, Jarle Tufto, Killian Farrell, René J. M. Stet, J. Coughlan, and Philip McGinnity
- Subjects
0106 biological sciences ,Genes, MHC Class I ,complex variation ,Balancing selection ,01 natural sciences ,class-ii loci ,polymorphism ,MHC (major histocompatibility complex) ,Salmo ,General Environmental Science ,Genetics ,0303 health sciences ,Natural selection ,biology ,natural selection ,General Medicine ,parasite resistance ,cryptococcus-neoformans ,bacterial-infection ,genetic-variation ,General Agricultural and Biological Sciences ,Research Article ,Atlantic salmon ,Genotype ,Genes, MHC Class II ,Salmo salar ,Locus (genetics) ,Celbiologie en Immunologie ,010603 evolutionary biology ,General Biochemistry, Genetics and Molecular Biology ,Evolution, Molecular ,03 medical and health sciences ,Rivers ,Genetic variation ,salar l ,Animals ,14. Life underwater ,Selection, Genetic ,Allele ,030304 developmental biology ,disease ,Polymorphism, Genetic ,Models, Genetic ,General Immunology and Microbiology ,biology.organism_classification ,populations ,Hatchery ,Genotype frequency ,Cell Biology and Immunology ,Linear Models ,WIAS ,Microsatellite Repeats - Abstract
Peer-reviewed. This document is the Accepted Manuscript version of a Published Work that appeared in final form in Proc. R. Soc. B. To access the final edited and published work see doi: 10.1098/rspb.2006.0053, Pathogen-driven balancing selection is thought to maintain polymorphism in major histocompatibility (MH) genes. However, there have been few empirical demonstrations of selection acting on MH loci in natural populations. To determine whether natural selection on MH genes has fitness consequences for wild Atlantic salmon in natural conditions, we compared observed genotype frequencies of Atlantic salmon (Salmo salar) surviving in a river six months after their introduction as eggs with frequencies expected from parental crosses. We found significant differences between expected and observed genotype frequencies at the MH class II alpha locus, but not at a MH class I-linked microsatellite or at seven non-MH-linked microsatellite loci. We therefore conclude that selection at the MH class II alpha locus was a result of disease-mediated natural selection, rather than any demographic event. We also show that survival was associated with additive allelic effects at the MH class II alpha locus. Our results have implications for both the conservation of wild salmon stocks and the management of disease in hatchery fish. We conclude that natural or hatchery populations have the best chance of dealing with episodic and variable disease challenges if MH genetic variation is preserved both within and among populations.
- Published
- 2007