Figure 2

Equilibrium abundance of the common pathogen type relative to the subordinate variant. The y axis shows the dominance ratio, D: the abundance of the common type divided by the abundance of the rare type. In general, the skew in abundances remains moderate until the parameters move near the boundary conditions for invasion shown in Figure 1. Near the boundary, the abundance of the rare type drops sharply, causing a steep rise in relative dominance by the common type. The x axis shows the cost, δ/β, for the rare type. The three curves in each panel show, from left to right, the values for R₀ = 2, 4, 8, which implies that β = k(1 + α) for k = 2, 4, 8. We used the parameters α = 10 and c = 1 to match the center panel of Figure 1. The left panel shows γ = 0.1, and the right panel shows γ = 1.