Rapid niche shifts in introduced species can be a million times faster than changes among native species and ten times faster than climate change.
Aims: As global temperatures rise, the survival of many species may hinge on whether they can shift their climatic niches quickly enough to avoid extinction. Previous analyses among species and populations suggest that species' niches change far slower than rates of projected climate change. However, it is unclear how quickly niches can change over the timeframe most relevant to global warming (decades instead of thousands or millions of years). Here, we use data from introduced species to assess how quickly climatic niches can change over decadal timescales. Location: Global. Methods: We analyse climatic data from 76 reptile and amphibian species introduced into the USA. We test for a relationship between species climatic-niche values in their native and introduced ranges. We also quantify niche shifts in introduced populations relative to their native ranges and the rate of change associated with these shifts. We then compare these rate estimates to those estimated among species and to projected rates of future climate change. Results: Remarkably, niche shifts in introduced species are roughly a million times faster than niche shifts among species in their native ranges and roughly 10 times faster than rates of projected climate change. Main conclusions: Our results demonstrate that dramatic and rapid niche shifts are possible, although these may be limited in species' native ranges by biotic interactions and other factors.