Wild salamanders have been shrinking as the result of having to burn more energy as their surrounding climate gets warmer, reports Clemson University in a study published Tuesday in the journal Global Change Biology.
For the study, researchers looked at salamanders caught in the Appalachian Mountains between the years of 1957 and 2007 as well as 2011 and 2012 and found that salamanders caught from 1980 onward were, on average, eight percent smaller than those from earlier years. The changes were most prevalent in the Southern Appalachians and at lower elevations where the weather has significantly warmed and dried over the years.
"One of the stresses warmer climates will impose on many organisms is warmer body temperatures," said Michael W. Sears of the biological sciences department. "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."
To see how these climate changes affected the animals the researchers used a computer program to create an artificial salamander, which allowed them to estimate how many calories it burned.Records researchers were able simulate minute-by-minute behavior based on recorded weather conditions. The simulations showed modern salamanders were just as active as their ancestors had been, although smaller.
"Ectothermic organisms, such as salamanders, cannot produce their own body heat," Sears explained. "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."
Their change in body size is one of the fastest rates of change ever recorded in an animal.
"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. If these animals are adjusting, it gives us hope that some species are going to be able to keep up with climate change," said Karen R. Lips, the paper's co-author, and an associate professor at the University of Maryland's (UMD) department of biology.
