Instead of treating lizard activity "as an on- or off-switch, we need to start thinking about activity as more of a dimmer switch, where behaviors are being dialed up and dialed down," says Manuel Leal. (Credit: Manuel Leal)

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Lizards aren’t so picky about ideal heat

Spring is here and ectotherms, or animals dependent on external sources to raise their body temperature, are becoming more active. Recent studies have shown that as the average global temperature increases, some lizards spend more time in the shade and less time eating and reproducing.

Like other cold-blooded animals, lizards have preferred body temperatures at which they hunt, eat, move quickly, and reproduce.

Lizards stay active over a broader range of temperatures than scientists previously thought, according to new research. When temperatures are either too hot or too cold, however, critical activity levels slow down.

Lizard activity

The active range for the Puerto Rican crested anole is between 81 and 84 degrees Fahrenheit (27-29 degrees Celsius). Previous research suggests lizards stop being active at hotter or cooler temperatures—but a new study offers a different perspective.

“We found that lizards were most active between the temperatures previously reported; however, above and below that range, lizards were still active,” says Manuel Leal, associate professor of biological sciences at University of Missouri.

“Although climate change is still a major problem for lizards, our research indicates that their activity levels are less constrained by temperature than previously thought.”

Dimmer switch

For the study, published online in the journal American Naturalist, Leal and Alex Gunderson, a postdoctoral fellow at the University of California, Berkeley, conducted behavioral observations and collected temperature data on hundreds of crested anoles in their native tropical habitat in Puerto Rico.

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They recorded the lizards’ movements and behaviors over 15-minute intervals and measured their body temperatures.

“The findings suggest that scientists need to rethink how to model the activity of ectotherms and how temperature rise due to climate change may affect behavior,” Leal says.

“Instead of treating activity as an on- or off-switch, we need to start thinking about activity as more of a dimmer switch, where behaviors are being dialed up and dialed down.”

The new modeling techniques presented in the study should provide scientists with the tools they need to create more targeted ways of determining the effects of climate variability on lizards’ activities, such as eating and reproducing, Leal says.

Source: University of Missouri

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