Fig. 2.
Ensemble results show error reduction over time and the effect of the diffusive mixing rate on regulation and extinctions. (a) Mean environmental error (Γ) in unperturbed/perturbed ensembles of 200 runs with F = 10 and RD = 1%. In the unperturbed ensemble (solid line), error decreases over time to an asymptote level. In the perturbed ensemble (dashed line), error is rapidly reduced from a spike after each perturbation. Data are plotted together with habitability bound (dotted line) and predicted environmental error in absence of life (dash-dot line). (b) Effect of mixing rate (RD, logarithmic scaling) on the final (asymptote) ensemble error value (dot markers, left ordinate; ensemble mean ± 1 SE) and the frequency of global extinction events (cross markers, right ordinate) after life has initially been established [F = 10, ensembles of 200 unperturbed runs for each mixing rate value in {0.01, 0.05, 0.1, 0.25, 0.5, 0.75, 1, 2.5, 5, 10, 20, 30, 50, 100} (%)]. Intermediate mixing rates provide the greatest error reduction and least frequency of global extinction. Runs in which initial seed did not become established are omitted.