Fig. 2.

Stochastic dynamics of a dominance game in small populations. (A) Three realizations of the stochastic dynamics in a small population with two types, X (blue) and Y (red) for $M=\mathrm{1,000}$. Stochastic trajectories deviate significantly from the deterministic dynamics (solid black lines). For example, in the third realization both types go extinct, first the dominant type X followed by type Y a little later. (B) Cumulative probability for the extinction of the entire population over time, averaged over ${10}^5$ realizations for different M (parameters ${\lambda }_{x\to xx}={\lambda }_{y\to yy}=0.6$, ${\lambda }_{x\to 0}={\lambda }_{y\to 0}=0.5$, $x_0=1$, and $y_0=9$; this yields $K^x=100$ and $K^y=25$ in the upper panel).