“…A potential explanation lies in the highly polygenic nature of lifeâhistory traits; it creates the opportunity for ample amount of nonadditive genetic variationâdominance, epistatic, and genotypeâbyâenvironment interactions (GEIs)âto exist. Recently, there have been studies quantifying dominance effects and epistasis (Armbruster, Bradshaw, & Holzapfel, 1997; Huang et al., 2012; Monnahan & Kelly, 2015), as well as the role of GEI in adaptation (e.g., Gutteling, Riksen, Bakker, & Kammenga, 2007; Jarosz & Lindquist, 2010; Rohner et al., 2013; for a review see Schlichting, 2008). Despite that, the pervasiveness of additiveâ and nonadditive variationâparticularly for competitive traitsâis still not yet well understood, especially in the context of environmental changes.…”