polygenic adaptation
de Vladar HP & Barton N 2014 Stability and response of polygenic traits to stabilizing selection and mutation. Genetics 197:749-767.
- understanding quantitative genetics in terms of population genetics is crucial for both scientific and practical reasons
- the joint effects of stabilizing selection and mutation lead to very complicated allele frequency equilibria and evolution
- it is not obvious how much genetic variation they can maintain
- an exact analysis in terms of allele frequencies is lacking for polygenic traits with loci of unequal effects
- this is desirable, as data from genome-wide association studies (GWAS) yield information about the distribution of single-nucleotide polymorphisms (SNPs) relevant to several traits based on population sequence data
- we aim to understand how a trait determined by arbitrarily many loci of unequal effects responds to stabilizing selection and mutation
- we regard this problem as fundamental to understanding the bigger picture of the evolution of polygenic traits, namely that of finite populations subject to drift and how these are constrained by pleiotropic effects caused by selection on multiple characters
- first, we need to understand in detail the nature of the equilibria and the response of allele frequencies to factors such as stabilizing selection and mutation
- we address the simplest case of deterministic selection on a single trait
- because of epistasis, we expect and in fact we find (Figure 8C) that some alleles that are initially beneficial increase in frequency, but afterward become detrimental and decrease in frequency again
- this "prevention of sweeps" has been observed in polygenic traits with up to eight loci (Pavlidis et al. 2012)
