A global phylogeny of butterflies reveals their evolutionary history, ancestral hosts and biogeographic origins

Abstract

Butterfies are a diverse and charismatic insect group that are thought to have evolved with plants and dispersed throughout the world in response to key geological events. However, these hypotheses have not been extensively tested because a comprehensive phylogenetic framework and datasets for butterfy larval hosts and global distributions are lacking. We sequenced 391 genes from nearly 2,300 butterfy species, sampled from 90 countries and 28 specimen collections, to reconstruct a new phylogenomic tree of butterfies representing 92% of all genera. Our phylogeny has strong support for nearly all nodes and demonstrates that at least 36 butterfy tribes require reclassifcation. Divergence time analyses imply an origin ~100 million years ago for butterfies and indicate that all but one family were present before the K/Pg extinction event. We aggregated larval host datasets and global distribution records and found that butterfies are likely to have frst fed on Fabaceae and originated in what is now the Americas. Soon after the Cretaceous Thermal Maximum, butterfies crossed Beringia and diversifed in the Palaeotropics. Our results also reveal that most butterfy species are specialists that feed on only one larval host plant family. However, generalist butterfies that consume two or more plant families usually feed on closely related plants.