title: The decline in fitness with inbreeding: evidence for negative dominance-by-dominance epistasis in Drosophila melanogaster.
abstract: Genetic interactions can play an important role in the evolution of reproductive strategies. In particular, negative dominance-by-dominance epistasis for fitness can theoretically favour sex and recombination. This form of epistasis can be detected statistically because it generates nonlinearity in the relationship between fitness and inbreeding coefficient. Measures of fitness in progressively inbred lines tend to show limited evidence for epistasis. However, tests of this kind can be biased against detecting an accelerating decline due to line losses at higher inbreeding levels. We tested for dominance-by-dominance epistasis in Drosophila melanogaster by examining viability at five inbreeding levels that were generated simultaneously, avoiding the bias against detecting nonlinearity that has affected previous studies. We find an accelerating rate of fitness decline with inbreeding, indicating that dominance-by-dominance epistasis is negative on average, which should favour sex and recombination.
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada.|Department of Zoology, University of British Columbia, Vancouver, BC, Canada.
authors.forename: N P
authors.identifier: http://orcid.org/0000-0001-6016-083X
authors.initials: NP
authors.lastname: Sharp
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada.
authors.forename: A F
authors.initials: AF
authors.lastname: Agrawal
mesh_terms: D000818:Animals; D004331:Drosophila melanogaster / Q000235:genetics / Q000502:physiology*; D004843:Epistasis, Genetic; D005260:Female; D007178:Inbreeding; D008297:Male; D011995:Recombination, Genetic / Q000235:genetics; D012098:Reproduction
keywords: dominance-by-dominance epistasis; inbreeding depression; mating system