Figure 2. Thin-Plate Spline Representations of Bivariate Fitness Surfaces for Male CHCs for Which Female Mating Preferences Evolved in Correlation with Treatment Environment.

(A) Visualization of the fitness surface of the two male CHCs for which linear sexual selection varied most among treatments.

(B) Visualization of the fitness surface of the two male CHCs for which nonlinear sexual selection varied most among treatments.

The four replicate populations within each treatment were pooled in each case. To aid in comparisons across treatments, a single smoothing parameter (λ) was chosen that gave the lowest generalized cross-validation score in all three treatments [43] separately for (A) (λ = −1.0) and (B) (λ = −0.2).