The evolutionary history of Boloria (Lepidoptera: Nymphalidae): phylogeny, zoogeography and larval–foodplant relationships

Abstract

Boloria is restricted to cooler regions of the northern hemisphere, and represents a model for understanding recent diversification of phytophagous insects in the Holarctic region. We infer the phylogeny of the genus based on characters from adult morphology and three genes (COI, EF1-α and wingless). We revise the subgenus level classification, and divide the genus into three subgenera, corroborating earlier works. The largest subgenus, Clossiana, is divided into nine informal species groups. A relaxed Bayesian clock analysis combined with a dispersal-vicariance analysis shows that the genus originated and first diversified in the Central Palaearctic region in the Middle Eocene. This region has remained important throughout the evolution of the genus, but independent diversifications also occurred in the Nearctic region. At least nine independent dispersal events between the Palaearctic and Nearctic regions are needed to explain the current distribution of the genus, whereas vicariance appears to have played only a minor role. An analysis of the evolution of larval–foodplant associations shows that although monophagous Violaceae-feeding is the original feeding strategy within Boloria, numerous host-shifts or broadenings of diet have happened. This inherent plasticity in host choice has likely been an important factor in the diversification in alpine and arctic environments by Boloria.