Florida Lizards Evolve Specialized Toes in as Little as 15 Years

It turns out that lizards in Florida are evolving far more quickly than anyone expected. Scientists working on islands have found that native lizard species evolved in as little as 15 years as a result of pressure from an invading lizard species.

The native species in question are called Carolina anoles, or green anoles. These lizards are common in the southeastern U.S. The invasive species, called brown anoles, are native to Cuba and the Bahamas. They first appeared in South Florida in the 1950s, probably as stowaways in shipments from Cuba.

In order to better understand the interaction between these two species, the scientists studied the lizards on Florida islands. They found that after contact with the invasive brown anoles, the green anoles began perching higher in trees. In fact, generation after generation, the feet on the green anoles evolved to become better at gripping the thinner and smoother branches found higher up.

"We did predict that we'd see a change, but the degree and quickness with which they evolved was surprising," said Yoel Stuart, one of the researchers, in a news release. "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 five foot nine inches today to about six foot four inches within 20 generations-an increase that would make the average U.S. male the height of an NBA shooting guard."

The findings reveal how pressures from outside forces can cause evolutionary change. Not only that, but the new study has become one of only a few well-documented examples of what is called "character displacement," which is when similar species competing with each other evolve differences to take advantage of different ecological niches.

The findings are published in the journal Science.