Cycad phylogeny predicts host plant use ofEumaeusbutterflies

Abstract

AbstractEumaeusbutterflies are obligate herbivores ofZamia, the most diverse neotropical genus of cycads.Eumaeus-Zamiainteractions have been mainly characterized for species distributed in North and Central America. However, host plant use by the southernEumaeusclade remains largely unknown, precluding a comprehensive study of co-evolution between the genera. Here, we combine fieldwork with museum and literature surveys to expand herbivory records forEumaeusfrom 21 to 38Zamiaspecies. We inferred a time-calibrated phylogeny ofEumaeusto test for distinct macroevolutionary scenarios of host plant conservatism and co-evolution. We found remarkable coincidence betweenEumaeusandZamiadiversification, with the butterfly stem group diverging at the same time as the most recent radiation ofZamiain the Miocene. Cophylogenetic reconciliation analyses show a strong cophylogenetic signal between cycads and their butterfly herbivores. Bipartite model-based approaches indicate that this is because closely relatedZamiaspecies are used by the sameEumaeusspecies, suggesting host plant resource tracking by the butterfly herbivores. Our results highlight a case of tight evolution betweenEumaeusbutterflies and cycads, pointing to the generality of correlated evolution and phylogenetic tracking in plant-herbivore interactions across seed plants.