title: Why organisms age: Evolution of senescence under positive pleiotropy?
abstract: Two classic theories maintain that aging evolves either because of alleles whose deleterious effects are confined to late life or because of alleles with broad pleiotropic effects that increase early-life fitness at the expense of late-life fitness. However, empirical studies often reveal positive pleiotropy for fitness across age classes, and recent evidence suggests that selection on early-life fitness can decelerate aging and increase lifespan, thereby casting doubt on the current consensus. Here, we briefly review these data and promote the simple argument that aging can evolve under positive pleiotropy between early- and late-life fitness when the deleterious effect of mutations increases with age. We argue that this hypothesis makes testable predictions and is supported by existing evidence.
authors.affiliation: Department of Animal Ecology, Evolutionary Biology Centre, Ageing Research Group, Uppsala University, Uppsala, Sweden.
authors.forename: Alexei A
authors.initials: AA
authors.lastname: Maklakov
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada.
authors.forename: Locke
authors.initials: L
authors.lastname: Rowe
authors.affiliation: Department of Evolutionary Biology, Evolutionary Biology Centre, Ageing Research Group, Uppsala University, Uppsala, Sweden.|IFM Biology, AVIAN Behavioural Genomics and Physiology Group, Linköping University, Linköping, Sweden.
authors.forename: Urban
authors.initials: U
authors.lastname: Friberg
mesh_terms: D000375:Aging; D000818:Animals; D005075:Biological Evolution; D058685:Genetic Pleiotropy; D006801:Humans; D009154:Mutation
keywords: aging; life-history evolution; mutation accumulation; positive pleiotropy; senescence