Lizards face extinction from global warming
Mica Rosenberg
Lizards are in danger of dying out on a large scale as rising global
temperatures force them to spend more time staying cool in the shade and
less time tending to basic needs like eating and mating.
Scientists warn in a research paper published on Thursday that if the
planet continues to heat up at current rates, 20 percent of all lizard
species could go extinct by 2080.
“The numbers are actually pretty scary,” said lead researcher Barry
Sinervo from the University of California Santa Cruz. “We’ve got to try
to limit climate change impacts right now or we are sending a whole
bunch of species into oblivion.”
A mass extinction of lizards, which eat insects and are eaten by
birds, could have devastating effects up and down the food chain, but
the extent is difficult to predict.
Sinervo made models of lizards with thermal monitors and left them in
the searing sun of southern Mexico to measure how the reptiles would
react to temperatures at different altitudes.
Lizards bask in the sun not to relax but for self-preservation. As
“ectotherms” they depend on the external environment to control their
body temperature.
Unlike mammals, when the reptiles overheat they cannot sweat or pant
and they have to retreat to the shade or burrow under a rock to cool
down.
This biological quirk has already led to the extinction of 5 percent
of lizard populations around the world, Sinervo said, as the creatures
spend more time scrambling to find shade and less time doing what they
need to do to survive. “Temperatures are rising too fast. Evolution
can’t keep up,” said Jack Sites, a herpetologist at Brigham Young
University who collaborated with Sinervo’s research.
Higher ground
Lizards come out during the day to warm up and use the time to find
food needed to breed.
“The warming temperatures sort of eclipse that activity period ... It
gets too hot to forage and they have to go back,” said Sites.
“So they don’t die directly but they can’t reproduce. It only takes a
couple of generations of that and the population is going to spiral
downward until it goes extinct.”
Reuters
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