Inter-annual variation in correlational selection acting jointly on fore and hindlimb lengths. Surfaces were produced using the cubic spline approach developed by Shluter and Nychka . The vertical axis shows the probability of survival (W) and each horizontal axis represents a standardized residual limb length. Surfaces range from convex to concave in wet years, but there was no curvature in the surface during the drought year.
Calsbeek et al. BMC Evolutionary Biology 2009 9:3 doi:10.1186/1471-2148-9-3