An experimental test of changed personality in butterflies from anthropogenic landscapes

Abstract

During the last century, the human footprint on natural ecosystems has increased strongly and human-altered habitats such as urban and agricultural areas have extended globally. Despite their negative impacts on biodiversity, these habitats offer unique opportunities to study how native species respond to novel environmental conditions. Here, we studied phenotypic divergence associated with colonization of human-altered habitats in the Speckled wood (Pararge aegeria). We reared butterflies of woodland, urban and agricultural origins under common garden conditions and we measured boldness and activity at the adult stage. Both behavioural traits were repeatable at the individual level (i.e. personality traits), but we found weak evidence for ecotype-related differences in mean boldness and activity. In line with urban areas being stressful habitats, we found that boldness and activity traits correlate in urban butterflies, while we found no such syndrome in woodland and agricultural butterflies. Our results show that urbanization can alter some aspects of personality in an insect species, but they do not support the prediction that anthropogenic habitats favour boldness. Human activities such as urbanization and intensive agriculture strongly alter terrestrial ecosystems and they are among the most significant threats to biodiversity. To tolerate human-dominated landscapes, many vertebrate species show behavioural shifts towards bold personalities, but similar responses remain rather overlooked in invertebrate taxa. Here, we studied the progeny of woodland, agricultural and urban Speckled woods reared under common garden conditions and we assessed their personality. We found little evidence for differences in personality traits among landscape types, but the behavioural syndrome linking boldness and activity was detected only in urban butterflies. This shows that urbanization can indeed shape some aspects of personality in invertebrates.