Figure 1.

Fitnesses and wild-type population in a deteriorating environment. (A) Fitnesses f_W, f_G, and f_S of the wild-type organisms (W), generalist (G), and specialist (S) mutants vs. time t (see Equations 1 and 2). Several values of the Hill coefficient n are shown for W. Inset: selection coefficient $s=f_M-f_W$ for both types of mutants M = G or S vs. time t, shown with n = 5 (and m = 5 for S mutants). (B) Number N_W of W microbes vs. time t for different values of n (same colors as in A). Data points correspond to averages over 10³ replicate stochastic simulations, and error bars (smaller than markers) represent 95% confidence intervals. Black solid curves correspond to numerical integrations of Equation 3. Parameter values: $g_W=g_S=g_G=0.1,$ K = 10³, $N_W^0=10,$ and θ = 10³. Vertical dotted line in both panels: t = θ.