Lizards Evolving Longer Hind Limbs to Survive Deadly Fire Ants

January 25, 2009

(ChattahBox) — Fire ants were accidentally introduced to the U.S. from South America in the 1930s, have no natural predators, in the U.S. and will eventually colonize more than 50 percent of Earth’s land surface. The ants have been known to strip animals as large as calves down to the bone. The venom-packed stings of just 12 fire ants can kill a three-inch-long (eight-centimeter-long) fence lizard in a minute, according to lead study author Tracy Langkilde, a biologist at Pennsylvania State University.

But some lizards are developing evolved traits of long legs and skittish behavior in the southeastern U.S. to co-exist with the lethal and invasive fire ants, according to a new study. The new findings could boost hopes for species whose habitats are quickly changing due to climate change, experts say. Study author Tracy Langkilde, a biologist at Pennsylvania State University found that longer hind limbs appear to help the lizards twitch and flee more effectively whenever ants attack, a defensive behavior that sheds the insects before they can pry up the reptiles’ scales and sting the soft flesh underneath. The findings, Langkilde said, are evidence of a rapid evolutionary response to the fire ants.

Langkilde, who received funding for her study from the National Geographic Society’s Committee for Research and Exploration, studied adult lizards from four populations and found that extended limbs and skittish tendencies were increasingly more common at sites where lizards and fire ants had co-existed longer. At a fire-ant-free site in Arkansas, for example, fewer than half the lizards responded when exposed to the venomous insects during an experiment. Most sat still, hoping the ants would go away, Langkilde noted.  The lizards were removed before any harm was done, she added.


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