Even though an invasive species is taking its territory, Florida’s native green anole lizard won’t go down without a fight. It’ll go up.
Scientists have shown that as a result of pressure from the invasive Cuban brown anole lizard, the green anole evolved stickier feet to help it climb higher in trees within 15 years.
The invasion of the Cuban lizard, which competed for the same food and ate the green anole hatchlings, forced the native anoles up higher into trees, where the branches are smoother. The lizard’s toe pads became larger and their feet grew more sticky scales within 20 generations, about 15 years.
“We did predict that we’d see a change, but the degree and quickness with which they evolved was surprising,” said Yoel Stuart, a postdoctoral researcher in the College of Natural Sciences at The University of Texas at Austin and lead author of the study.
“To put this shift in perspective, if human height were evolving as fast as these lizards’ toes, the height of an average American man would increase from about 5 foot 9 inches today to about 6 foot 4 inches within 20 generations — an increase that would make the average U.S. male the height of an NBA shooting guard,” Stuart said. “Although humans live longer than lizards, this rate of change would still be rapid in evolutionary terms.”
The adaptation is similar to a classic Darwinian example of “character displacement,” in which species evolve to better survive in ecological niches, a press release on the study notes. Charles Darwin documented Galápagos Islands finches evolving differently shaped beaks to take advantage of different food sources.
The fact that anoles like to make a meal of baby anoles of another species also provided a more immediate “survival of the fittest” motivation, the scientists say.
“So it may be that if you’re a hatchling, you need to move up into the trees quickly or you’ll get eaten,” said Stuart. “Maybe if you have bigger toe pads, you’ll do that better than if you don’t.”
[Source: University of Texas]
Green Anole image via Wikimedia Commons