polygenic adaptation - senecio7の日記

Wollstein A & Stephan W 2014 Adaptive fixation in two-locus models of stabilizing selection and genetic drift. Genetics 198:685-697.

selection on an adaptive character involves simultaneous selection at multiple loci controlling the trait
this may cause small to moderate allele-frequency shifts at these loci
adaptation does not require new mutations in the short term
selection uses alleles found in the standing variation of a population

in contrast to quantitative genetics, in population genetics and genomics our understanding of the genetics of adaptation has revolved in recent years around the role of selective sweeps

can the quantitative genetics models of stabilizing selection also be used to predict observed levels of selective fixations?
Chevin and Hospital (2008) presented a model for the footprint of positive directional selection at a quantitative trait locus (QTL) in the presence of a fixed amount of background genetic variation due to other loci
this approach is based on Lande’s (1983) model
QTL of adaptive traits under stabilizing selection exhibit patterns of selective sweeps only very rarely
de Vladar and Barton (2011, 2014) studied a polygenic character under stabilizing selection, mutation, and genetic drift
they found sweeps after abrupt shifts of the phenotypic optimum, without quantifying how often such signatures occurred
Pavlidis et al. (2012) analyzed a classical multilocus model with two to eight loci controlling an additive quantitative trait under stabilizing selection (with and without genetic drift)
multilocus response to selection often prevents trajectories from going to fixation, particularly for the symmetric viability model
the probability of fixation strongly depends on the genetic architecture of the trait