Supplementary material from "Manipulation of natal host modifies adult reproductive behaviour in the butterfly Heliconius charithonia"

Advances in understanding non-genetic inheritance have prompted broader interest in environmental effects. One way in which such effects may influence adaptation is via the transmission of acquired habitat biases. Here I explore how natal experience influences adult host orientation in the oligophagous passion vine butterfly Heliconius charithonia. As an exemplar of the ‘pupal mating' system, this species poses novelty among diurnal Lepidoptera for the extent to which male as well as female reproductive behaviours are guided by olfactory host cues. I sampled wild adult females breeding exclusively upon Passiflora incarnata, assigned their offspring to develop either upon this species or its local alternative Passiflora suberosa, and then assessed the behaviour of F1 adults in a large rainforest enclosure. Despite the fact that juvenile performance was superior upon P. incarnata, females oviposited preferentially upon their assigned natal species. Mate-seeking males also indicated a bias for the proximity of their natal host, and there was evidence for assortative mating based upon host treatment, although these data are less robust. This study is, to my knowledge, the first to support Hopkins' hostplant principle in butterflies, and points to inducible host preferences capable of reinforcing ecological segregation and ultimately accelerating evolutionary divergence in sympatry.