biostudies-literatureUnknownDevi AAlthough many phenotypic traits are determined by a large number of genetic variants, how a polygenic trait adapts in response to a change in the environment is not completely understood. In the framework of diffusion theory, we study the steady state and the adaptation dynamics of a large but finite population evolving under stabilizing selection and symmetric mutations when selection and mutation are moderately large. We find that in the stationary state, the allele frequency distribution at a locus is unimodal if its effect size is below a threshold effect and bimodal otherwise; these results are the stochastic analog of the deterministic ones where the stable allele frequency becomes bistable when the effect size exceeds a threshold. It is known that following a sudden shift in the phebioRxiv : the preprint server for biology2023.01.25.525607https://www.ebi.ac.uk/biostudies/studies/S-EPMC9901025biostudies-literaturePolygenic adaptation dynamics in large, finite populations.PMC9901025Devi AJain KfalsePolygenic adaptation dynamics in large, finite populations.Although many phenotypic traits are determined by a large number of genetic variants, how a polygenic trait adapts in response to a change in the environment is not completely understood. In the framework of diffusion theory, we study the steady state and the adaptation dynamics of a large but finite population evolving under stabilizing selection and symmetric mutations when selection and mutation are moderately large. We find that in the stationary state, the allele frequency distribution at a locus is unimodal if its effect size is below a threshold effect and bimodal otherwise; these results are the stochastic analog of the deterministic ones where the stable allele frequency becomes bistable when the effect size exceeds a threshold. It is known that following a sudden shift in the phe2023-01-01T00:00:00Z2023 Jan2025-04-04T10:58:23.846Z2025-04-04T10:58:23.846ZS-EPMC99010253674782910.1101/2023.01.25.525607