Fig 3. Frequency of population extinction in the CA model depends on the initial population size.

(a) Stochastic fluctuations lead to extinction or growth. The figure shows the frequency of extinction events depending on averaged cell density $\tilde{\varrho }=|ℒ{|}^{-1}{\displaystyle \sum _{r\in ℒ}\varrho }(r)$. (b) Probability density function (derived by kernel density estimates, see S1 Text) of the averaged cell density after 5000 LGCA time steps for three different initial population densities. For each initial configuration 40 simulation runs are performed. Model parameters are κ = 4.4, θ = 0.75, r _b = 0.2, r _d = 0.01, K = 8. Cases (i), (ii) and (iii) refer to different initial population densities, which show bimodal (case (i) and (ii)) or unimodal (case (iii)) stationary size distributions.