Extreme weather events like the recent storm Harvey in Texas offer an opportunity to study the effect of rapid natural selection. During the winter of 2013–2014, the southeastern United States, including Texas and Oklahoma, was subjected to an extreme cold snap with low temperatures that had not been experienced for at least 15 years. In a recent article researchers studied and compared the effect of cold on green anole lizards from Hodgen, Oklahoma (34.8° N) south to Brownsville, Texas (25.9° N) near the Mexican border. It is known that in the green anole lizard cold tolerance is heritable and different populations have developed different tolerances to cold. In addition the genome of the green anole lizard has been sequenced (reported in 2011). In the study the behaviour and genetic composition of anole lizards were examined before and after the extreme cold weather event. It was found that in the extreme southern range (Brownsville), lizards sampled in the Spring after the cold snap showed greater tolerance of low temperature and greater genetic differences compared to lizards sampled before the cold snap. The researchers were able to identify specific genes that correlated with latitude. This study demonstrates that natural selection induced by extreme events can induce rapid changes in the behaviour and genetic makeup of lizards. This finding has implications for different species as extreme events become more prevalent.
Winter storms drive rapid phenotypic, regulatory, and genomic shifts in the green anole lizard, Shane C. Campbell-Staton, Zachary A. Cheviron, Nicholas Rochette, Julian Catchen, Jonathan B. Losos, Scott V. Edwards, Science 04 Aug 2017, Vol. 357, Issue 6350, pp. 495-498, DOI: 10.1126/science.aam5512