Fig. S10.

The gradual enhancer switching model results in a more downwardly concave effective speed gradient than the applied gradient. Shown are computer simulations of the gradual enhancer switching model at different positions along the spatial axis (i.e., different values of the applied gradient, gray). Equal changes in applied gradient values result in unequal changes in speeds of sequential activation. Specifically, changes around lower values of the gradient induce bigger changes in speed, resulting in a downwardly concave effective speed gradient (gray outlined in yellow).