Range expansion of an already widespread bee under climate change

Abstract

Climate change is a key threat to pollination networks and has already caused shifts in the distribution and phenology of many bee species. Predictions based on species distribution models forecast that most bee species will continue to decline as climate change progresses, the few exceptions to this being common, widespread species with large dispersal capabilities. Most of the bees studied so far are temperate or tropical species but many ecosystems are predicted to experience increased aridification under climate change. Therefore, we need to understand how pollinator species are likely to respond. Here we present species distribution models for the arid-adapted Australian small carpenter bee, Ceratina australensis Perkins, 1912 (Apidae: Xylocopinae) under Intergovernmental Panel on Climate Change (IPCC) climate change conditions predicted for 2070 (Representative Carbon Pathway 8.5). We applied Maximum Entropy, Generalized Linear Models, Generalized Additive Models and Random Forest methods. Overall, our models predict that this bee will have an increased area of suitable habitat as climate change progresses, including an increased range within protected areas. However, its potential range will shift further into coastal areas, that are highly human populated and urbanised. Our results suggest that wild bee taxa may be able to cope with the predicted scale of future aridification under climate change. Finally, this species is predicted to increase in urban environments, which highlights the need for city planning, suitable habitats and green spaces to support wild bee species. Keywords: Climate change, Species distribution modelling, Pollinator, Wild bee, Arid zone, Ceratina