Shrinking size of North American salamanders linked to climate change


Biologists are reporting another example of a species being impacted by climate change, describing how wild salamanders in some North American habitats are shrinking in a warmer and drier environment.

Writing in the journal Global Change Biology describes comparison of museum specimens caught in the Appalachian Mountains from 1957 to 2007 with wild salamanders, measured at the same sites in 2011-2012.

In the Southern Appalachians, where precise weather data shows a warming trend, salamanders in studies from 1980 and forward were discovered to be as much as 8 percent smaller than those from earlier decades, Biologists found.

"One of the stresses that warmer climates will impose on many organisms is warmer body temperatures," Clemson University researcher Michael W. Sears says. "These warmer body temperatures cause animals to burn more energy while performing their normal activities. All else being equal, this means that there is less energy for growth."

Salamanders are in of a class of animals known as ectothermic organisms, which cannot generate their own body heat but must take their heat from their immediate environment.

Using a computer model to estimate a typical salamander's daily activity and the amount of calories it burned, Sears found the activity of today's salamanders the same as that of their ancestors, even as their habitats become warmer and drier.

"Their metabolism speeds up as temperatures rise, causing a salamander to burn seven to eight percent more energy in order to maintain the same activity as their forebears," Sears added.

Sears co-authored the study published in the journal Global Change Biology with University of Maryland biology Professor Karen R. Lips.

The shrinking body size of salamanders is one of the most significant and quickest rates of change ever recorded in any animal strongly linked to climate change, Lips says.

"We do not know if decreased body size is a genetic change or a sign that the animals are flexible enough to adjust to new conditions," Lips said. "If these animals are adjusting, it gives us hope that some species are going to be able to keep up with climate change."

Lips and Sears say ongoing research will compare salamander species that are getting smaller but surviving to species that are disappearing from parts of their traditional range, in an effort to understand why salamanders are declining in North American habitats that were once some of the best for salamanders in the world.

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