Climate change and biological invasions are two primary threats to global biodiversity, and it has been hypothesized that these factors will operate synergistically in the future to favor, and thus facilitate the spread of, non-native species. To date, this hypothesis has primarily been developed based on local comparisons of single or few demographic responses and lacks general support. We took a meta-analytical approach to address whether non-native species are poised for greater success in future climatic conditions across ecosystems. We created a database of 89 published papers with 132 studies from aquatic and terrestrial ecosystems that reported demographic rates under different climatic conditions for both non-natives and sympatric native species. This included demographic responses of 204 native and 157 non-native species across four climate-change scenarios: warming temperature, increased CO2, increased precipitation, and decreased precipitation.
Results/Conclusions
We found that non-native species were more likely to respond to changes in CO2 and precipitation availability than the corresponding native species. However, non-native species’ responses were not uniformly positive and varied between aquatic and terrestrial systems. Specifically, increased CO2 was associated with positive responses of non-native species overall, and this pattern was driven by terrestrial (primarily plant) species. Conversely, decreased precipitation had a significant negative effect on non-native, as well as native, species. Interestingly, while responses to temperature were highly variable, they suggested the opposite trend, with natives responding more strongly than non-native species. Finally, in aquatic systems, non-native species were favored over native species in future temperature and CO2 conditions. There is, thus, some indication that non-native species may benefit most from – or tolerate best – global increases in temperature, CO2, and precipitation yet also suffer the most under climate change when precipitation becomes scarce.