Lizard Popsicles, Anyone?

Dr. Espinoza and his co-authors found that Liolaemus lizards have adapted abilities to deal with the cold through three mechanisms. Some lizards avoid extreme cold by going underground. Others use a process of supercooling; by staying completely still, they can allow their bodies to drop below freezing without actually freezing solid. Finally, some can also tolerate full-body freezing for short periods of time. Dr. Espinoza said that some Liolaemus species likely made use of more than one mechanism, depending on the conditions.

The strategy of full-body freezing is likely similar to that seen in North American wood frogs, which stay frozen over winter thanks to an antifreeze-like glucose solution that protects the cells; Dr. Espinoza still needs to investigate this hypothesis to be sure. The world’s southernmost gecko, Darwin’s marked gecko, another Argentine lizard that Dr. Espinoza has studied, most likely adopts the supercooling strategy.

Lizards of many colors

The reason Liolaemus lizards can withstand such cold temperatures and high elevations may also explain why there are so many of the lizards. Whereas there were only about 50 described to science when Dr. Halloy worked on them in the late 1970s, there are now 272 species.

Dr. Espinoza and others have discovered a number of species, and his occasional co-author Fernando Lobo, a zoologist at the National University of Salta in Argentina, has discovered 30 or more species of Liolaemus and its close cousin, the genus Phymaturus. In one case, Dr. Lobo discovered a species under his tent, in cloudy, frozen weather in the Argentine province of Santa Cruz near the Chilean border.

“They didn’t look like any of the others,” Dr. Lobo said. “We suspected they were a new one. We’ve had that excitement dozens of times in these 25 years.”

At the current rate of discovery, Liolaemus will likely become the most numerous genus of living mammals, reptiles and birds in coming years.