An unusually cold winter in the U.S. in 2014 took a toll on the green anole lizard, a tree-dwelling creature common to the southeastern United States. A new study offers a rare view of natural selection in this species, showing how the lizard survivors at the southernmost part of their range in Texas came to be more like their cold-adapted counterparts further north.

The study is reported in the journal Science.

“We were able to track natural selection at the level of the whole organism, but also at the level of gene sequence and gene expression,” said University of Illinois postdoctoral researcher Shane Campbell-Staton, who led the new research. “I think this is a really strong and clear story about biological responses to extreme weather events.”