UM lizard study observes natural selection in single Southland winter

The research focused on the effects of natural selection in green anole lizards. (University of Montana)

A cold snap in the South led a University of Montana scientist to realize that a species of lizard had responded to the chilly weather by shifting its gene patterns to resemble its northern kin, lending insight to the process of natural selection.

Those animals that adapted survived the strangely cold winter while those that didn’t perished, possibly taking other significant gene traits with them.

“We know that selection occurs at a cost – death,” said Shane Campbell-Staton, the study’s lead at UM. “It’s possible that the individuals that died as a result of this cold snap may have had the genetic and physiological tools to survive a drought or a heat wave, and now those lineages are lost. We still have a lot to learn about how predicted patterns of extreme weather will impact biodiversity.”

The study, “Winter storms drive rapid phenotypic, regulatory and genomic shifts in the green anole lizard,” made the latest issue of the journal Science.

Campbell-Staton, a postdoc fellow at UM, said the research focused on the effects of natural selection in green anole lizards after an extreme cold-weather event in the southeastern U.S. during the winter of 2013-14.

While the unpredictable nature of extreme weather makes it difficult to study natural selection responses, the winter of 2013-14 presented a unique opportunity.

“Unless you happen to have data before such an event and can get data directly after, it can be very difficult to test hypotheses about their impacts,” Campbell-Staton said. “Our study is unique in that we had data before and after this extreme weather event, and we were able to measure selection at three levels.”

The study found significant increases in cold tolerance at the species’ southern limit. Gene expression in southern survivors shifted toward patterns characteristic of northern populations.

“We conclude that extreme winter events can rapidly produce strong shifts in natural populations at multiple biological levels,” he said. “The fact that we saw such a strong shift in the southern population within the course of a single calendar year was quite surprising.”

Campbell-Staton said the research raises larger questions about the long-term consequences of extreme weather events for these populations.

“When most people think about climate change, they think about the gradual warming our planet is undergoing,” Campbell-Staton said.

“But another major symptom of modern climate change is the increase in frequency and magnitude of extreme weather events like cold snaps, heat waves and droughts. Although brief in nature, these types of events can have profound effects on natural populations for many generations.”