Classical quantitative genetics has found that most phenotypes are polygenic traits. Under this polygenic model, natural selection often acts on many loci simultaneously, resulting in the combination of a few loci with major effects and many loci with small effects controlling adaptive changes in phenotypes, which presents challenges to the understanding of the genetic basis underlying polygenic traits.
Click here for original story, Novel major locus regulates beak evolution of ground tit
Source: Phys.org