Fig. 1. Evolution of host–plant association through time shows strong host–plant conservatism across swallowtail butterflies.

Phylogenetic relationships of swallowtail butterflies, with coloured branches mapping the evolution of host–plant association, as inferred by a maximum-likelihood model (Supplementary Figs. 4 and 6). Additional analyses with two other maximum-likelihood and Bayesian models inferred the same host–plant associations across the phylogeny (Supplementary Fig. 5). Lue. Luehdorfiini, Zerynth. Zerynthiini, T. Teinopalpini. Pictures of butterflies made by Fabien Condamine.