Invasive species unchecked by climate - response

Hulme points out that observed rates of range expansion by invasive alien species are higher than the median speed of isotherm movement over the past 50 years, which in turn has outpaced the rates of climate-associated range changes of marine and terrestrial species. This is not surprising, given the many ecological and anthropogenic processes that combine to facilitate the translocation of invasive species and the subsequent expansion of their populations.

Successful alien species have been observed to rapidly expand their ranges until some limit, typically climate-imposed, is reached. Comparisons of climate-change-induced range shifts between native and alien species are meaningful only after the initial invasive spread has reached a stable range boundary.

A focus on regions with high velocities of climate change, and on regions such as the tropics where novel thermal niches are being created, should allow researchers to collect data to test hypotheses about the role of climate in driving range shifts of invasive and native species. It is important to remember that the distinctions among native and alien species will be blurred under rapid global change as both types expand their ranges into novel environments.

This may be particularly true in the world's boreal oceans as melting sea ice facilitates new migratory passages between the Atlantic and Pacific Oceans. Moreover, as the ebb and flow of biodiversity intensifies under anthropogenic climate change, novel climates and communities of species will develop.

Policy will not only have to address the threats of alien invasions, but also have to deal with rapid range shifts of native species and with the threats to species that are unable to adapt or move. Climate change is redefining management strategies and conservation goals and concepts.