title: A general condition for adaptive genetic polymorphism in temporally and spatially heterogeneous environments.
abstract: Both evolution and ecology have long been concerned with the impact of variable environmental conditions on observed levels of genetic diversity within and between species. We model the evolution of a quantitative trait under selection that fluctuates in space and time, and derive an analytical condition for when these fluctuations promote genetic diversification. As ecological scenario we use a generalized island model with soft selection within patches in which we incorporate generation overlap. We allow for arbitrary fluctuations in the environment including spatio-temporal correlations and any functional form of selection on the trait. Using the concepts of invasion fitness and evolutionary branching, we derive a simple and transparent condition for the adaptive evolution and maintenance of genetic diversity. This condition relates the strength of selection within patches to expectations and variances in the environmental conditions across space and time. Our results unify, clarify, and extend a number of previous results on the evolution and maintenance of genetic variation under fluctuating selection. Individual-based simulations show that our results are independent of the details of the genetic architecture and whether reproduction is clonal or sexual. The onset of increased genetic variance is predicted accurately also in small populations in which alleles can go extinct due to environmental stochasticity.
authors.affiliation: Mathematics and Biosciences Group, Department of Mathematics, University of Vienna, 1090 Vienna, Austria. Electronic address: hannes@svardal.at.
authors.forename: Hannes
authors.initials: H
authors.lastname: Svardal
authors.affiliation: Mathematics and Biosciences Group, Department of Mathematics, University of Vienna, 1090 Vienna, Austria; Animal Ecology, Department of Ecology and Genetics, Uppsala University, 752 36 Uppsala, Sweden. Electronic address: claus.rueffler@ebc.uu.se.
authors.forename: Claus
authors.initials: C
authors.lastname: Rueffler
authors.affiliation: Mathematics and Biosciences Group, Department of Mathematics, University of Vienna, 1090 Vienna, Austria; Max F. Perutz Laboratories, 1030 Vienna, Austria. Electronic address: joachim.hermisson@univie.ac.at.
authors.forename: Joachim
authors.initials: J
authors.lastname: Hermisson
mesh_terms: D000818:Animals; D003198:Computer Simulation; D004777:Environment; D019143:Evolution, Molecular; D014644:Genetic Variation; D005828:Genetics, Population / Q000379:methods*; D006801:Humans; D008957:Models, Genetic; D011110:Polymorphism, Genetic; D012098:Reproduction / Q000235:genetics; D012641:Selection, Genetic; D062211:Spatio-Temporal Analysis
keywords: Coexistence; Evolutionary branching; Frequency dependence; Island model; Lottery model; Soft selection