Figure 6.

Evolution of heterogeneity during long-term stress.A. Candida sake isolates obtained from the control location at Site 2 (Fig. 3), with differing basal heterogeneities (□), were subcultured daily to MYP broth supplemented with 30 μM Pb(NO₃)₂ for ≥ 500 generations, before heterogeneity (of Pb resistance) for each was assayed again (▪).B. Mean values ± SEM of the data from (A) and from a parallel control experiment where the isolates were cultured for ≥ 500 generations in unsupplemented MYP broth. The phenotypes evolved after ≥ 500 generations were heritably stable (see main text). * P < 0.05, ** P < 0.01.