Flight endurance and heating rate vary with both latitude and habitat connectivity in a butterfly species


S. Ducatez, Mus. Natl d’Histoire Naturelle, Dépt Ecologie et Gestion de la Biodiversité, 57 rue Cuvier, FR-75005 Paris cedex 5, France. Present address for SD: Dept of Biology, McGill Univ., 1205 avenue Docteur Penfield, Montréal, QC, A H3A 1B1, Canada. E-mail: simon.ducatez@mail.mcgill.ca


Environmental factors at both macro-ecological and landscape scales are likely to affect (meta) population dynamics and species distributions, through direct or indirect effects on individual phenotypes. Although disentangling these scale effects is of prime importance in evolutionary ecology and conservation biology, most studies dealing with the links between phenotype and the environment have mainly focused on the landscape scale, and none has addressed the interactions between effects at both scales. In ectotherms, movement abilities are strongly dependent upon thermoregulation abilities, and thus likely vary with latitude. Moreover, in such species, movement is also highly dependent upon landscape geometry at the landscape scale. Here, we quantified the combined effects of latitude and habitat fragmentation on movement ability in relation with thermoregulation abilities in the butterfly Pieris brassicae as model for understanding the relative contributions of macro-ecological and landscape scale effects on species’ mobility. We sampled individuals at an early developmental stage (eggs or caterpillars), in natural populations from 27 sites with different degrees of habitat connectivity, along a latitudinal gradient across France and Belgium. Adult flight and heating rate were measured in laboratory controlled conditions and were used as proxies for movement ability and thermoregulation ability, respectively. We found that flight endurance for both sexes and female heating rate increased with latitude. Habitat connectivity had a sex-dependent effect on both traits: flight endurance in males increased with decreasing habitat connectivity, while the opposite was found in females. Moreover, heating rate increased with increasing habitat connectivity, the effect being stronger in males. Overall, our results highlight the need to integrate intraspecific variation in movement ability at different spatial scales when studying species’ responses to global environmental change.