Fig. 3. Genotype by environment interaction (G×E) of gene expression.

a Reaction norms between environment A and B for two genotypes a and b. Points of the same color represent the same genotype; the slope of the lines connecting points of the same color indicate the magnitude of the change in genetic value for that genotype between the two environments. Significant differences in slope for different genotypes signify the presence of G×E. In this example, there is G×E but no change in genetic variance between the two environments. b No mean effect of temperature but significant G×E and change in genetic variance between the two environments. c The same data as in b but plotted with respect to difference between genotypes across the two environments. d Example of a gene (sosie) in females with low degree of G×E. e Example of a gene (Cp15) with a high degree of G×E in females. G×E is defined as $\mathrm{G\times E}={\sigma }_{\mathrm{GE}}^2/\left({\sigma }_{\mathrm{GE}}^2+{\sigma }_G^2\right)$. f Distribution of G×E for genes in females, where significant genes are marked by dark red color. g Distribution of G×E for genes in males, where significant genes are marked by dark blue color.