Cool Customer

Scientists expect that many tropical animals, such as lizards, won’t be able to cope with a fast-changing climate. But in The American Naturalist, researchers report that at least one lizard species can quickly adapt to changing temperatures.

Lizards and other ectotherms rely largely on heat sources in their environment and are thought to be especially vulnerable to climate change. The Puerto Rican crested anole lizard, which spread to Miami in the 1970s, offered the study authors a chance to test this hypothesis. The coldest winter days in Miami are 10 degrees Celsius lower than the coldest days in Puerto Rico, so the lizards would need to adapt to chillier weather to survive.

The researchers collected these lizards from Puerto Rico and Miami, then tested the animals’ cold tolerance in the lab. First, the team tied each lizard to a cardboard rectangle with dental floss and put the animal into an incubator set at 2 degrees Celsius. After the lizard’s body had cooled to a certain temperature — between 7 and 14 degrees Celsius — it was taken out of the incubator and set on its back. If the animal couldn’t get back up again, that body temperature was considered to be beyond the lizard’s tolerance limit.

The Miami lizards could tolerate temperatures 3.1 degrees Celsius lower than the Puerto Rican lizards could, the team found. The result “is unexpected and provides a glimpse of hope for tropical lizards under the current conditions of rapid climate change,” the researchers write.

They performed similar experiments to test the lizards’ heat tolerance and didn’t find a difference, which makes sense since Miami and Puerto Rico have similar maximum temperatures. More studies will be needed to determine whether lizards can adapt just as quickly to hotter weather. — Roberta Kwok | 21 November 2012

Source: Leal, M. and A.R. Gunderson. 2012. Rapid change in the thermal tolerance of a tropical lizard. The American Naturalist doi: 10.1086/668077.

Image © Geoff Gallice | Wikimedia Commons