Figure 3.

The continuously stable strategies (CSSs) level of investment in immunity. White regions indicate no immunity (μ = 0) with darker shadings indicating a greater level of immunity. For clarity, we plot contours for every 0.1 increment in investment (the bold line gives the μ = 0 contour). (A) Varying death rate, b, and waning immunity, (δ) (B) varying virulence, α, and sterility, f₁ (C) varying recovery, γ, and transmission, β. We also show plots for how the density of immune hosts at the CSS (solid line) and a fixed level of μ (dashed line) for varying (D) waning immunity, δ, and (E) virulence, α. Default parameter values are as of figure 1 with λ = 2. In (D) b = 0.1.