Century-long butterfly range expansions in northern Europe depend on climate, land use and species traits

Climate change is an important driver of range shifts and community composition changes. Still, little is known about how the responses are influenced by the combination of land use, species interactions and species traits. We integrate climate and distributional data for 131 butterfly species in Sweden and Finland and show that cumulative species richness has increased with increasing temperature over the past 120 years. Average provincial species richness increased by 64% (range 15-229%), from 46 to 70. The rate and direction of range expansions have not matched the temperature changes, in part because colonisations have been modified by other climatic variables, land use and vary according to species characteristics representing ecological generalisation and species interactions. Results emphasise the role of a broad ecological filtering, whereby a mismatch between environmental conditions and species preferences limit the ability to disperse and establish populations in emerging climates and novel areas, with potentially widespread implications for ecosystem functioning. Century-long data on climate and butterfly distribution show that species richness has increased with increasing temperature, and that the rate and direction of range expansions are influenced by land use, species interactions and species traits.

Automated summary

Climate change is a crucial factor in driving changes in range shifts and community composition. The combination of land use, species interactions, and species traits also influences these responses, although the details are not well understood. By integrating climate and distribution data for 131 butterfly species in Sweden and Finland, we found that cumulative species richness has increased with rising temperatures over the past 120 years. However, the rate and direction of range expansions do not align with temperature changes due to the influence of other climatic variables, land use, and species characteristics.