Nonlinear Dynamics in Gene Regulation Promote Robustness and Evolvability of Gene Expression Levels
G-P mappings of circuit I (a-c) and circuit II (d-f), showing the density of genotypes on the map. Three different combinations of robustness/evolvability measures are shown in each case. The first column (a and d) shows the relationship between sensitivity-based robustness and scaled intrinsic noise (small mutational effects); the second column (b and e) shows sensitivity-based robustness against evolvability computed using 1-mutant neighbors, represented by 40% parameter perturbations on average (small mutational effects versus large mutational effects); the third column (c and f) shows robustness against evolvability when both are computed using 10% parameter perturbations (large mutational effects). Red colors indicate areas on the G-P mapping that are highly populated by genotypes.