An extremely cold spell in the southeastern United States in the winter of 2013–14 drove remarkably rapid change in local lizard populations.
Shane Campbell-Staton of the University of Illinois at Urbana–Champaign and his colleagues compared green anole lizards (Anolis carolinensis) collected before and after this event at five sites, from Brownsville in the far south of Texas to Hodgen, Oklahoma, further north. The southernmost survivors of the winter showed significantly higher cold tolerance than individuals sampled from the same location a year earlier. Gene expression in these animals had also shifted to be closer to that of more northerly lizards, which tend to experience colder weather.
Extreme weather can have drastic effects on local populations and drive physical and genetic changes, the authors say.