polygenic adaptation
Bod'ová K, Tkacik G & Barton NH 2016 A general approximation for the dynamics of quantitative traits. Genetics 202:1523-1548.
- we cannot hope to predict the evolution of quantitative traits by using a direct population genetics approach based on the frequencies of each individual allele
- selection, captured by the mean fitness W, may be an arbitrary function of the distribution of quantitative traits, which, in turn, may be an arbitrary function of the n allele frequencies
- a central result in population genetics is that the stationary distribution of allele frequencies is the product of the neutral distribution and the mean fitness raised to the power of population size
- ψ ∼ ϕW2N
- we assume additivity across loci
- de Vladar and Barton (2011) show how the method applies to stabilizing selection, which induces pairwise epistasis between loci
- when 4Nμ < 1, sudden changes in population size and mutation rate cause immediate changes at the boundaries
- the distribution deviates from the stationary form
- —which is the problem that we address here
- fitness differences determine the rate of adaptation
- they do not measure the outcome
- by drastically reducing the dimensionality of the system to cover only the expectations of selected quantities, we can simplify expressions for the total fitness flux and variance in fitness over the evolutionary trajectory
