Oviposition site selection and learning in a butterfly under niche expansion: an experimental test

Organisms that colonize new habitats may gain fitness advantages from changes in habitat selection including oviposition behaviour. Variation in oviposition site selection may contribute to ecological differentiation in response to novel ecological conditions. Both inherited and environmentally induced or learned differences may contribute to variation in preoviposition search behaviour and oviposition site selection. We addressed this issue with the speckled wood butterfly, Pararge aegeria. Over recent decades, this species has expanded its habitat use by colonizing anthropogenic environments with populations that show differences in several phenotypic traits (i.e. ecotypes). Here we tested whether preoviposition search behaviour and oviposition site selection differ between field-derived females from forested and agricultural ecotypes, and whether prior experience would change their behaviour differently. We used F1-offspring reared under common garden laboratory conditions and observed individuals of both ecotypes repeatedly in an indoor experimental arena. The arena offered compartments with host plants under simulated open and woody landscape conditions, as well as control compartments. In contrast with predictions, ecotypic differences in preference were found not for a particular microhabitat, but rather for oviposition site versus control compartment. Nevertheless, exploration and microhabitat use differed between females of agricultural and forest ecotypes. Furthermore, we provide evidence of short-term (i.e. a few hours after initial exposure) learning in the context of preoviposition search behaviour, pointing at the often ignored role of habitat familiarization. Our study sheds new light on behavioural changes that relate to habitat use in novel environments for a species that thrives successfully in landscapes under rapid human-induced environmental change. (c) 2021 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.