Body size, not species identity, drives body heating in alpineErebiabutterflies

Abstract

Efficient thermoregulation is crucial for animals living under changing climatic and weather conditions. We used a thermal camera to measure thermoregulation of six co-occurring species of Erebia (Lepidoptera: Nymphalidae) mountain butterflies in a laboratory experiment with artificial light and heating source. We studied wild individuals to test whether physical characteristics (body size, wing loading) are responsible for the interspecific differences in thermoregulation detected previously under natural conditions in European Alps. We revealed that physical characteristics had a small effect on explaining interspecific differences compared to distinct thermoregulatory differences recorded in the field. Our results show that larger butterflies, with higher weight and wing loading, heated up more slowly but reached the same asymptotic body temperature as smaller butterflies. Altogether, our results suggest that differences in body temperatures among Erebia species observed in the field are likely caused mainly by species-specific differences in microhabitat use and confirm the role of active thermoregulation in adult butterflies.