"We find that, over the next 90 years, at best these species' ranges will change more than 100 times faster than they have during the past 320,000 years," said Michelle Lawing, lead author of the paper and a doctoral candidate in geological sciences and biology at IU Bloomington. "This rate of change is unlike anything these species have experienced, probably since their formation."

The study, "Pleistocene Climate, Phylogeny, and Climate Envelope Models: An Integrative Approach to Better Understand Species' Response to Climate Change," was published by the online science journal PLoS ONE. Co-author is P. David Polly, associate professor in the Department of Geological Sciences in the IU Bloomington College of Arts and Sciences.

The researchers make use of the fact that species have been responding to climate change throughout their history and their past responses can inform what to expect in the future.
They synthesize information from climate cycle models, indicators of climate from the geological record, evolution of rattlesnake species and other data to develop what they call "paleophylogeographic models" for rattlesnake ranges. This enables them to map the expansion and contraction at 4,000-year intervals of the ranges of 11 North American species of the rattlesnake genus Crotalus.