Polygenic adaptation in changing environments

TL;DR

This paper investigates how polygenic traits adapt to changing environments, revealing that the genetic architecture influences the speed of adaptation, with larger effect sizes enabling faster response.

Contribution

It provides a theoretical analysis of the adaptation dynamics of polygenic traits under stabilising selection and environmental change, highlighting the role of genetic architecture.

Findings

Mean trait moves linearly with environmental change

Speed of adaptation depends on effect sizes of genetic variants

Larger effect sizes lead to faster adaptation

Abstract

Although many phenotypic traits are determined by a large number of genetic variants, how a polygenic trait adapts in response to the changes in the environment is still poorly understood. Here we study the adaptation dynamics of a polygenic trait that is determined by a finite number of genetic loci in an infinitely large population which is evolving under stabilising selection and recurrent mutations. We find that in a changing environment, modeled here by a linearly moving phenotypic optimum, the mean trait also moves linearly with time. But its speed is smaller than that of the phenotypic optimum when the effect sizes of the genetic variants are small and approaches that of the environmental change for larger effect sizes. Our study thus highlights the influence of the genetic architecture of a polygenic trait on its adaptability.