Figure 2.

Association between fitness and conjunctival swelling. We show fitness (measured as the product of putative infection duration and transmission rate) as a function of mean conjunctival swelling (in pixels), with greater fitness being associated with intermediate values of mean conjunctival swelling. The two isolates with the highest fitness were collected from two different years; evidence of selection on intermediate values of mean conjunctival swelling remained even when they were removed from the analysis (GAM; parametric linear effect ± se = 0.08 ± 0.009, t = 9.2, P < 0.0001; spline (non‐linear) effects, F_1.6,2.0 = 5.8, P < 0.006). Points represent jittered raw values; the line is predicted from the model with the standard error represented by the ribbon.