Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Tropical lizards can't take the heat of climate warming

From geckos and iguanas to Gila monsters and Komodo dragons, lizards are among the most common reptiles on Earth. They are found on every continent except Antarctica. One even pitches car insurance in TV ads. They seemingly can adapt to a variety of conditions, but are most abundant in the tropics.

However, new research that builds on data collected more than three decades ago demonstrates 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," said Huey, lead author of a paper outlining climate warming's threat to lizards published in the March 4 Proceedings of the Royal Society B. The Royal Society is Great Britain's national academy of science.

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, Huey said, 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.

A lizard in Washington, for example, might experience a temperature range of 40 degrees or more between summer and winter, while one in Puerto Rican forests might only experience a range of 20 to 25 degrees.

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 lizard's 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. Subsequent laboratory work by Huey and others tested the sprinting speeds for more than 70 species of lizards at varying body temperatures.

"In the 1970s a bunch of us were running around the Caribbean with thermometers taking lizard body temperatures for reasons totally unrelated to climate warming. But we can use our data from a third a century ago as a baseline to now predict how lizards at different latitudes would respond to climate change," Huey said.

His co-authors are Curtis Deutsch of the University of California, Los Angeles; Joshua Tewksbury of the UW; Laurie Vitt of the University of Oklahoma; Paul Hertz of Barnard College; Héctor Álvarez Pérez of the University of Puerto Rico; and Theodore Garland Jr. of the University of California, Riverside. The work was funded by the National Science Foundation and the UW Program on Climate Change.

Huey's lizard studies in the early 1970s included a species called Anolis gundlachi that lived in a forest at about 1,000 feet elevation near El Verde, Puerto Rico. The shaded forest was an ideal environment for Anolis gundlachi, but was too cool for another species, A. cristatellus, that favored the warmer conditions found in unforested habitats nearby.

But since the early 1970s, Huey said, the average temperature in the forest has risen from just less than 80 degrees Fahrenheit to nearly 83.5 F, which should be stressfully warm for A. gundlachi and almost warm enough for A. cristatellus. Scientists believe the tropics could warm by another 5 degrees F by the end of this century.

"That may not sound like much, but we think gundlachi is going to get hammered because it will suffer heat stress from the warmer temperatures," Huey said.

To make matters worse, if temperatures become warm enough A. cristatellus could well move into the forest, forcing A. gundlachi to deal with a formidable competitor that it doesn't have now.

The assessment does not look at potential effects of climate change on the forest canopy, Huey said, and that could make matters worse. If warming stresses the trees so that the leafy canopy at the top of the forest becomes more open, then the amount of solar radiation reachng the forest floor will further increase the ambient temperature. This will add to the stress of species such as A. gundlachi.

It also is possible the lizards could adapt evolutionarily to the warmer conditions, Huey said, "but we don't think it's likely because of their long generation times." The scientists also believe the same concerns apply to other ectotherms, such as snakes, insects and spiders, that live on land in tropical forests.

"Because tropical forest lizards aren't very heat tolerant and they live in environments that are already warm, any further warming could push them over the edge," Huey said.

Vince Stricherz | EurekAlert!
Further information:

More articles from Ecology, The Environment and Conservation:

nachricht Dispersal of Fish Eggs by Water Birds – Just a Myth?
19.02.2018 | Universität Basel

nachricht Removing fossil fuel subsidies will not reduce CO2 emissions as much as hoped
08.02.2018 | International Institute for Applied Systems Analysis (IIASA)

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Space observation with radar to secure Germany's space infrastructure

Satellites in near-Earth orbit are at risk due to the steady increase in space debris. But their mission in the areas of telecommunications, navigation or weather forecasts is essential for society. Fraunhofer FHR therefore develops radar-based systems which allow the detection, tracking and cataloging of even the smallest particles of debris. Satellite operators who have access to our data are in a better position to plan evasive maneuvers and prevent destructive collisions. From April, 25-29 2018, Fraunhofer FHR and its partners will exhibit the complementary radar systems TIRA and GESTRA as well as the latest radar techniques for space observation across three stands at the ILA Berlin.

The "traffic situation" in space is very tense: the Earth is currently being orbited not only by countless satellites but also by a large volume of space...

Im Focus: Researchers Discover New Anti-Cancer Protein

An international team of researchers has discovered a new anti-cancer protein. The protein, called LHPP, prevents the uncontrolled proliferation of cancer cells in the liver. The researchers led by Prof. Michael N. Hall from the Biozentrum, University of Basel, report in “Nature” that LHPP can also serve as a biomarker for the diagnosis and prognosis of liver cancer.

The incidence of liver cancer, also known as hepatocellular carcinoma, is steadily increasing. In the last twenty years, the number of cases has almost doubled...

Im Focus: Researchers at Fraunhofer monitor re-entry of Chinese space station Tiangong-1

In just a few weeks from now, the Chinese space station Tiangong-1 will re-enter the Earth's atmosphere where it will to a large extent burn up. It is possible that some debris will reach the Earth's surface. Tiangong-1 is orbiting the Earth uncontrolled at a speed of approx. 29,000 km/h.Currently the prognosis relating to the time of impact currently lies within a window of several days. The scientists at Fraunhofer FHR have already been monitoring Tiangong-1 for a number of weeks with their TIRA system, one of the most powerful space observation radars in the world, with a view to supporting the German Space Situational Awareness Center and the ESA with their re-entry forecasts.

Following the loss of radio contact with Tiangong-1 in 2016 and due to the low orbital height, it is now inevitable that the Chinese space station will...

Im Focus: Alliance „OLED Licht Forum“ – Key partner for OLED lighting solutions

Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, provider of research and development services for OLED lighting solutions, announces the founding of the “OLED Licht Forum” and presents latest OLED design and lighting solutions during light+building, from March 18th – 23rd, 2018 in Frankfurt a.M./Germany, at booth no. F91 in Hall 4.0.

They are united in their passion for OLED (organic light emitting diodes) lighting with all of its unique facets and application possibilities. Thus experts in...

Im Focus: Mars' oceans formed early, possibly aided by massive volcanic eruptions

Oceans formed before Tharsis and evolved together, shaping climate history of Mars

A new scenario seeking to explain how Mars' putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

New solar solutions for sustainable buildings and cities

23.03.2018 | Event News

Virtual reality conference comes to Reutlingen

19.03.2018 | Event News

Ultrafast Wireless and Chip Design at the DATE Conference in Dresden

16.03.2018 | Event News

Latest News

For graphite pellets, just add elbow grease

23.03.2018 | Materials Sciences

Unique communication strategy discovered in stem cell pathway controlling plant growth

23.03.2018 | Agricultural and Forestry Science

Sharpening the X-ray view of the nanocosm

23.03.2018 | Physics and Astronomy

Science & Research
Overview of more VideoLinks >>>