Fig. 3: Natural selection on limb length during the incipient stages of character displacement.

A–D Univariate selection surfaces of relative forelimb and hind limb length for A. sagrei before and after invasion by A. cristatellus. Solid lines represent the fitted logistic regression model; dashed lines represent ± 1 S.E. Relative limb lengths (x-axes) represent body size-corrected residuals; values below and above 0 represent relatively smaller and larger limb lengths, respectively. Gray points represent individual lizards; bottom row survival = 0 and higher row survival = 1 (the y-axis has been truncated for visual purposes). E, F Three-dimensional selection surfaces that estimate survival probability as a function of the correlated relationship between relative forelimb and relative hind limb length; heat colors represent survival probability. All points underneath the selection surfaces represent individual lizards: red points are survivors; unfilled circles are non-survivors. All p-values in (A–F) are from multivariate selection models following Lande & Arnold⁸⁹. ^·p < 0.10, *p < 0.05; **p < 0.01. All source data are available at: https://doi.org/10.6084/m9.figshare.27165759; data for (A–F) from file “NatComms_ECD_selection_data”.