Fig. 4
From: Why and how genetic canalization evolves in gene regulatory networks
Extreme phenotypic optima. In a six-gene network, one gene is selected for the minimum expression, one for the maximum expression, the four remaining being free to evolve. a Evolution of gene expression. Filled areas stand for the s.d. across 200 replicates (not shown for the non-selected genes as their distribution is bimodal). Statistics were mesured every 500 generations. b Evolution of canalization score (negative log of the variance of mutational effects). c Distribution of gene expression values at the last generation (G=10,000). d Distribution of regulatory effects (W ij ) at the last generation (immutable 0s are discarded from the analysis). The vertical dotted line stands for the absence of regulation