Figure 4.

B ₂ blocks adsorption, Sequential presentation. Effects of Sequential presentation: alternating growth on pure B₁ versus pure B₂. (a) growth on B₁ every third cycle. (b) Mixed presentation results from Fig. 3a are provided for comparison. There is little difference from Sequential in (a). (c) Growth on B₁ every sixth cycle is slightly worse for mutant evolution than every third cycle, mirroring the effect of low B₁ levels observed for Mixed presentation. (d) Effect of cycle length (B₁ every third cycle). The same qualitative effects of exposure to B₁ and cycle length are observed with Sequential presentation as with Mixed presentation. In (d), P₂ levels are taken within a minute of cycle’s end once 580 min have elapsed; the contour jaggedness stems from the boosting effect of growth on B₁ versus B₂ and that the timing of B₁ cycles relative to P₂ sampling varies with cycle length. Parameter values are as given in Fig. 1; k₁₂ = 0.