title: Response to Selection in Finite Locus Models with Nonadditive Effects.
abstract: Under the finite-locus model in the absence of mutation, the additive genetic variation is expected to decrease when directional selection is acting on a population, according to quantitative-genetic theory. However, some theoretical studies of selection suggest that the level of additive variance can be sustained or even increased when nonadditive genetic effects are present. We tested the hypothesis that finite-locus models with both additive and nonadditive genetic effects maintain more additive genetic variance (VA) and realize larger medium- to long-term genetic gains than models with only additive effects when the trait under selection is subject to truncation selection. Four genetic models that included additive, dominance, and additive-by-additive epistatic effects were simulated. The simulated genome for individuals consisted of 25 chromosomes, each with a length of 1 M. One hundred bi-allelic QTL, 4 on each chromosome, were considered. In each generation, 100 sires and 100 dams were mated, producing 5 progeny per mating. The population was selected for a single trait (h2 = 0.1) for 100 discrete generations with selection on phenotype or BLUP-EBV. VA decreased with directional truncation selection even in presence of nonadditive genetic effects. Nonadditive effects influenced long-term response to selection and among genetic models additive gene action had highest response to selection. In addition, in all genetic models, BLUP-EBV resulted in a greater fixation of favorable and unfavorable alleles and higher response than phenotypic selection. In conclusion, for the schemes we simulated, the presence of nonadditive genetic effects had little effect in changes of additive variance and VA decreased by directional selection.
authors.affiliation: Center for Quantitative Genetics and Genomics, Department of Molecular Biology and Genetics, Aarhus University,  Tjele, Denmark.
authors.forename: Hadi
authors.initials: H
authors.lastname: Esfandyari
authors.affiliation: Seges, Danish Pig Research Centre, Copenhagen, Denmark.|School of Animal Biology, University of Western Australia, Crawley, Australia.
authors.forename: Mark
authors.initials: M
authors.lastname: Henryon
authors.affiliation: Center for Quantitative Genetics and Genomics, Department of Molecular Biology and Genetics, Aarhus University,  Tjele, Denmark.|Nordic Genetic Resource Center, Ås, Norway.
authors.forename: Peer
authors.initials: P
authors.lastname: Berg
authors.affiliation: Center for Quantitative Genetics and Genomics, Department of Molecular Biology and Genetics, Aarhus University,  Tjele, Denmark.|VikingGenetics, Assentoft, Denmark.
authors.forename: Jørn Rind
authors.initials: JR
authors.lastname: Thomasen
authors.affiliation: Animal Breeding and Genomics Centre, Wageningen University, Wageningen, The Netherlands.
authors.forename: Piter
authors.initials: P
authors.lastname: Bijma
authors.affiliation: Center for Quantitative Genetics and Genomics, Department of Molecular Biology and Genetics, Aarhus University,  Tjele, Denmark.
authors.forename: Anders Christian
authors.initials: AC
authors.lastname: Sørensen
mesh_terms: D000465:Algorithms; D005799:Genes, Dominant; D014644:Genetic Variation; D005828:Genetics, Population; D016678:Genome; D005838:Genotype; D008957:Models, Genetic; D010641:Phenotype; D040641:Quantitative Trait Loci; D012641:Selection, Genetic
keywords: finite locus model; nonadditive effects; selection