Comparisons of models with alternate smooth terms (temperature – year) for each species and morphological trait.

Δdf and ΔDeviances describe the differences between paired models (GAMs), with negative values indicating that the model including “year” as a smooth term explains more variance than the model including “temperature” as the smooth term. P-values were calculated from F-tests, whose degrees of freedom were Δdf. For contrasts in which the degrees of freedom differed by less than 1, no statistical comparisons were possible.