As the world , much less the climate, changes, species must change and move too. A species ability to overcome adversity goes beyond Darwin’s survival of the fittest. In a new study based on simulations examining species and their projected range, researchers at Brown University argue that whether an animal can make it to a final, climate-friendly destination isn’t a simple matter of being able to travel a long way. It’s the extent to which the creatures can withstand rapid fluctuations in climate along the way that will determine whether they complete the journey. In a paper in Ecology Letters, Regan Early and Dov Sax examined the projected climate paths of 15 amphibians in the western United States to the year 2100. Using well-known climate forecasting models to extrapolate decades-long changes for specific locations, the researchers determined that more than half of the species would become extinct or endangered. The reason, they find, is that the climate undergoes swings in temperature that can trap species at different points in their travels. It’s the severity or duration of those climate swings, coupled with the given creature’s persistence, that determines their fate.