The evolution of proboscis length and feeding behaviour in hawkmoths (Lepidoptera: Sphingidae)

Abstract Hawkmoths (Lepidoptera: Sphingidae) display some of the most extraordinary and iconic morphological adaptations. They are well known to have long proboscides, which have evolved to obtain nectar from flowers with deep tubes. Proboscides of some hawkmoths reach nearly five times their body length, but other species have mouthparts that have become completely non-functional. Adult nectar feeding is thought to have been gained and lost multiple times across the family but has never been formally tested. Here, we examine this evolution of proboscis length and feeding behaviour. We constructed a dated phylogeny of Sphingidae using a 537 locus anchored hybrid enrichment dataset, sampling 168 of the 205 sphingid genera (approx. 82%). We inferred a robust phylogeny and conducted ancestral state reconstructions of adult feeding behaviour, revealing the evolution of feeding gains and losses. Our results show that adult feeding in hawkmoths first evolved around 44 Ma, with the sphingid subfamilies diverging during the Eocene. Based on patterns exhibited in our phylogenetic analyses, it is possible that multiple independent transitions in feeding behaviour have occurred over the evolutionary history of this family. This research provides a novel contribution to understanding the evolution and ecology of an economically and environmentally important insect lineage.