Tropical lizards may be in serious threat from global warming

March 4th, 2009 - 3:04 pm ICT by ANI  

Washington, March 4 (ANI): A new research has indicated that lizards living in tropical forests in Central and South America and the Caribbean could be in serious peril from rising temperatures associated with climate change.

In fact, those forest lizards appear to tolerate a much narrower range of survivable temperatures than do their relatives at higher latitudes and are actually less tolerant of high temperatures, said Raymond Huey, a University of Washington biology professor.

The least heat-tolerant lizards in the world are found at the lowest latitudes, in the tropical forests. I find that amazing, he added.

It has often been assumed that tropical organisms are much better at dealing with high temperatures than those in colder climates because the lowland tropics are always warm.

But that assumption is only true to a point, because those in the tropical forest experience a much narrower range of temperatures during the year and are rarely, if ever, exposed to extreme high temperatures, Huey said.

Forest conditions tend to keep lizards living there at temperatures that allow them to function at or close to their physical peak.

A temperature change of just a few degrees can reduce their physical performance greatly.

Lizards are ectotherms, regulating their body temperature by exchanging heat with their surroundings.

Huey originally collected data on body temperatures of lizards in a Puerto Rican forest in 1973, and later measured how fast they can sprint at various body temperatures.

Sprinting relates directly to survivability because it affects a lizards ability to hunt or elude predators.

He found that even at the coolest and warmest parts of the day, the forest lizards functioned at least at 90 percent of their maximum ability, because the temperatures varied so little and were optimal then for these lizards.

Scientists believe the tropics could warm by another 5 degrees F by the end of this century.

Though that may not sound much, but tropical lizards are going to get hammered because they will suffer heat stress from the warmer temperatures, according to Huey.

Because tropical forest lizards arent very heat tolerant and they live in environments that are already warm, any further warming could push them over the edge, Huey said. (ANI)

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