Environmental variation, fluctuating selection and genetic drift in subdivided populations

• Published in: Theoretical population biology Vol. 74; no. 3; pp. 233 - 250
• Main Author: Taylor, Jesse E.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.10.2008
• Subjects: Diffusion approximation; Environmental variation; Fluctuating selection; Genetic Drift; Genetics, Population; Haploidy; Island model; Levene model; Markov Chains; Population subdivision; Selection, Genetic; Stochastic Processes; Diffusion approximation; Genetic drift; Environmental variation; Fluctuating selection; Island model; Population subdivision; Levene model
• ISSN: 0040-5809; 1096-0325; 1096-0325
• DOI: 10.1016/j.tpb.2008.07.005

Although there have many studies of the population genetical consequences of environmental variation, little is known about the combined effects of genetic drift and fluctuating selection in structured populations. Here we use diffusion theory to investigate the effects of temporally and spatially varying selection on a population of haploid individuals subdivided into a large number of demes. Using a perturbation method for processes with multiple time scales, we show that as the number of demes tends to infinity, the overall frequency converges to a diffusion process that is also the diffusion approximation for a finite, panmictic population subject to temporally fluctuating selection. We find that the coefficients of this process have a complicated dependence on deme size and migration rate, and that changes in these demographic parameters can determine both the balance between the dispersive and stabilizing effects of environmental variation and whether selection favors alleles with lower or higher fitness variance.