Personality variation is linked to environmental differences between edge and core habitats in a flightless insect

Abstract

Individuals with different personalities (i.e. consistent behavioural differences between individuals) probably vary in their ability to cope with certain environmental conditions, with ecological and evolutionary implications in both natural and human-altered environments. Theory suggests that personality differences are important when studying edge effects (i.e. changed environmental conditions at habitat edges compared to cores) and wider biodiversity responses, but empirical studies are lacking. Here, we examined whether a flightless woodland-dwelling ground beetle species, Abax parallelepipedus, exhibits personality differences in exploratory behaviour. We also investigated whether exploratory behaviour and body size differ between edge and core woodland habitats, and whether these differences can be explained by environmental conditions in these habitats. Almost 800 individuals from nine edge and nine core woodland habitats were studied in standardized novel environment tests in the field for their exploratory behaviour, and a subset was brought into the laboratory for repeated testing. Individuals showed personality differences, with higher exploration in core habitats compared to edge habitats, while body size did not differ systematically across habitats. Core and edge habitats differed in many environmental variables, for example aspects of ground vegetation cover, leaf litter depth, A. parallelepipedus density and canopy cover, and some environmental variables explained variation in exploration but not body size. For instance, exploratory behaviour increased with depth of leaf litter, which was higher in core than in edge habitats. We show that edge effects favoured different behaviours and potentially selected for different personalities than conditions in core habitats, possibly impacting intraspecific (behavioural) diversity, population dynamics and species interactions. Our results advance the understanding of intraspecific variation in behaviour in heterogeneous environments and are important given ongoing human-induced habitat fragmentation, which increases the amount of edge habitats.