The pace of range expansion: a long-term study on the flightless ground beetle Carabus hortensis (Coleoptera: Carabidae)

Abstract

Range shifts are predicted for numerous species due to climate change, and therefore understanding species dispersal is more crucial than ever. For some species, their low dispersal capabilities may prevent them from reaching new, suitable habitats, thus threatening their survival. This is of particular concern for those ground beetles which are flightless and depend on a specific type of habitat. However, studies on ground beetle dispersal rates are rare. We investigated the shift in distribution range of Carabus hortensis in northwestern Germany over a span of 22 years. We found that this species disperses on average 127 m per year with low variation between years. Although C. hortensis’ movement (locomotory) activity is not different or lower than that found in similar ground beetles, its dispersal rate is rather low. We speculate that this slow range expansion may be due to a long individual development time from egg to teneral and suggest that in the face of climate change, conservation actions, like assisted migration, may be an option for such slow dispersing species.