Predicting the effect of climate change on aggregation behaviour in four species of terrestrial isopods

Climate warming has changed the spatial distributions and temporal behaviours of several taxa. A key question that remains is how behaviours that alter microclimatic conditions might be used to buffer the effects of climate change. In this study, we focus on the aggregation behaviour of four species of terrestrial isopods, in which groups of individuals clump together to prevent moisture-loss, and use a laboratory protocol to investigate the effects of changes in relative humidity (RH) and temperature on aggregation. We find that three species aggregate more at lower RH and at higher temperatures, and that species that are better adapted to reducing moisture loss aggregate less than do species with fewer such adaptations. These results suggest that behavioural variation can buffer the effects of changes in microclimate. We finish by suggesting that it is critical to determine how such behavioural shifts will affect isopod densities and competitive hierarchies.