Fig. 4.

The effects of transitioning from regular to random networks on strain diversity and discordance. (A) The effect of ρ (the degree of host mixing) on mean discordance (dashed line) and mean diversity (solid line) for two simulations. The simulation denoted with the open circle has parameter values C = 10, r = 0.0681, τ = 0.0049, γ = 2.8178, β = 0.4093, 1/μ = 8, 1/σ = 11, P = 481, n = 4. The simulation denoted with the open square has parameter values C = 8, r = 0.0554, τ = 0.0021, γ = 3.5578, β = 0.7262, 1/μ = 9, 1/σ = 15, P = 371, n = 3. (B) The degree of host clustering, measured by the clustering coefficient, as a function of ρ. The clustering coefficient is defined and computed as in Watts and Strogatz (14). (C) The average size of the largest strain cluster as a function of ρ. The decrease in discordance and the increase in diversity with more localized interactions (lower ρ) is strongly correlated to the degree of host clustering and the growth in the size of the largest strain cluster. Both simulations were run for 5,000 time steps, for each of the 14 ρ values, ranging from 0.0001 to 1. The first 2,000 time steps were discarded to remove the effect of transients. Note the logarithmic scale on the x axis.