Phylogenetic relationships of the tribe Operophterini (Lepidoptera, Geometridae): A case study of the evolution of female flightlessness

Abstract

A molecular phylogenetic analysis was conducted in order to reconstruct the evolution of female flightlessness in the geometrid tribe Operophterini (Lepidoptera, Geometridae, Larentiinae). DNA variation in four nuclear gene regions, segments D1 and D2 of 28S rRNA, elongation factor 1α, and wingless, was examined from 22 species representing seven tribes of Larentiinae and six outgroup species. Direct optimization was used to infer a phylogenetic hypothesis from the combined sequence data set. The results obtained confirmed that Operophterini (including Malacodea) is a monophyletic group, and Perizomini is its sister group. Within Operophterini, the genus Malacodea is the sister group to the genera Operophtera and Epirrita, which form a monophyletic group. This relationship is also supported by morphological data. The results suggest that female flightlessness has evolved independently twice: first in the lineage of Malacodea and, for the second time, in the lineage of Operophtera after its separation from the lineage of Epirrita. An alternative reconstruction (i.e. recovery of flight ability in an ancestor of Epirrita) appears unlikely for various reasons. The similarities shared by Epirrita with a basal representative of Perizomini, Perizoma didymatum, allow the proposal of a sequence of evolutionary events that has led to flightlessness. It is likely that the transition to female flightlessness in the two lineages of Operophterini occurred after the colonization of stable forest habitats, followed by the evolution of a specific set of permissive traits, including larval polyphagy, limited importance of adult feeding, and adult flight during the cold months of the season. © 2007 The Linnean Society of London.