Advance, retreat, resettle? Climate change could produce a zero-sum game for invasive species

Climate change will alter the threats presented by invasive species. Increasing temperatures and changing precipitation regimes will likely simultaneously improve the suitability of a region for some species while decreasing it for others. We demonstrate the zero-sum game nature of these changes by modelling the changes to the projected distribution of 13 tropical and subtropical Tephritidae species in cities in Australia and New Zealand using published CLIMEX models. Under current climate conditions, tropical and warm temperate cities were suitable for more species than arid or cool temperate ones. All New Zealand cities increased in suitability, while Australian cities show more variable responses. The changes that occur under climate change are in line with the expectation of species ranges moving into higher latitudes but are also influenced by changes to the precipitation regime. With climate change, the nature of biosecurity threats will alter, the range of species able to survive in cool temperate regions is likely to increase with decreases in species ability to survive in tropical regions. Biosecurity agencies will need to respond to changing geography of threats.