Pairwise Invasibility Plots (PIP) illustrating the effect of increasing the ratio of host mortality to lethargy rates on the evolution of virulence.

In the paper, Parasite-induced shifts in host movement may explain the transient coexistence of high- and low-pathogenic disease strains, we investigate the effect of varying the ratio of host mortality to lethargy rates on the evolution of virulence. The ratio is b = ratio of host mortality to lethargy rates values from 0 to 0.05. The x-axis and y-axis are the resident and the mutant parasite replication rates respectively. Virulence depends on parasite replication rate within the host. For a combination resident-mutant parasite replication rates, white colour indicates that the mutant goes extinct and white colour indicates that the mutant replaces the resident parasite at the endemic equilibrium. The intersections are evolutionary equilibria, and intersections where the colour is white at the top bottom are evolutionarily stable trait values, whereas intersections where the colour is black at the top and bottom are invisible repellor. See paper for details