Frequency of different pathway structures during the course of evolution. Different panels show results from sample simulations with increasing probability for protein recruitment (P(rcrtmnt)) in expense of interaction formation (i.e. results from one of the runs used to create Figure 4). Red, blue and black lines show the frequency of modular, crosstalk, and complex pathways (see the legend of Figure 4 for pathway types). Note, that measurements are taken after mutations but before selection, hence there is a small fraction of unconnected pathways at each generation (not shown on the graph).