“Gradient variation evolves when environmental and genotypic effects on a phenotype covary positively (cogradient variation) or negatively (countergradient variation) across locations, whereas gene-by-environment interactions (G × E) reflect nonadditive genetic and environmental influences on phenotypes. Spatial covariance in environmental and genotypic effects (Cov_GE) shapes variation in quantitative traits, facilitates local adaptation, and provides insights into eco-evolutionary dynamics.”

Find the paper and full list of authors at The American Naturalist.