Figure 5. Contrasting outcomes for equilibrium prevalence (A and B) and host density (C and D) from hypothetical epidemiological models that illustrate dynamics that rise when fitness traits (survival and fecundity) and infectivity (transmission rate) vary with stressors, as demonstrated by our meta-analysis results. A and C are simulation outcomes of SI-Resource model. The half-saturation transmission constant (ht) determines the transmission rate (β) response to resource availability, where a greater value of ht makes the β less sensible to resources, and vice versa. B and D are simulation outcomes of SI-Environmental stress model. In the model, β could have different sensitivities to environmental factors (βE), ranging from positive to negative. For parameters used in each model simulation, see Box 1 and 2, respectively.