Complex evolution in thin air: Investigating female flightlessness and diel behaviour in geometrid moths (Lepidoptera)

Abstract

Many unique high-altitude mountain ecosystems have been declining due to climate change, posing a threat to flora and fauna that have adapted to these ecosystems. This study explores the evolution of high-altitude adaptations, focusing on female flightlessness and diel activity, in geometrid moths (Lepidoptera: Ennominae, Gnophini) within the European Alps. We constructed a phylogeny of Gnophini moths using a dataset of 157 taxa, with up to seven genetic markers and traced the evolutionary history of diel activity and wing length reduction in females. Analysis of divergence times suggested that female flightlessness has evolved at least three times independently between the early and late Miocene. The evolution of wing length reduction is likely correlated with elevation, indicating adaptations to cold and windy conditions in high altitude. The evolutionary events leading to shifts in adult diel activity, from ancestral nocturnality to diurnality, have occurred independently at least three times and may also be a consequence of adaptations at high elevations. Strikingly, among diurnal Sciadia, two species have evolved further to become nocturnal like their ancestors. Our findings highlight how phylogenies can provide new insights into evolutionary patterns in moths. We provided a robust basis for resolving taxonomic ambiguities in Alpine Gnophini, leading us to propose 10 changes to the current classification: Scrupodes Lee & Sihvonen gen. n., Elophos Boisduval (type species Geometra operaria Hübner) is considered a junior synonym of Sciadia Hübner syn. n., Yezognophos dilucidaria (Denis & Schiffermüller) and Y. sproengertsi (Püngeler) are transferred to Parietaria Leraut comb. n., Yezognophos serotinaria (Denis & Schiffermüller) is transferred to Scrupeus Lee & Sihvonen comb. n., Elophos caelibaria (Heydenreich), E. zirbitzensis (Pieszcek), E. operaria (Hübner) and E. andereggaria (De La Harpe) are transferred to Sciadia Hübner comb. n. and Dichrognophos Wehrli (type species Gnophos orthogonia Wehrli) is transferred from Ennominae: Cassymini to Ennominae: Gnophini.