Figure 3.

A schematic cartoon of rewiring. A schematic cartoon of rewiring with (left) and without (right) cooperative binding. Selection favours a change in the regulation of target genes from the red TF to the green TF. Rewiring requires an initially deleterious mutation at the red binding site before a green binding site can be acquired. The fitness of the different states is shown on the left hand side for each case. The reduced fitness of the intermediate state is less when cooperative binding is present than when it is absent.