Debunking Darwin: scientists witness quick, visible physical evolution in tree lizards

Evolution moves slowly -- too slowly to see it happen. That's been the general consensus among scientists ever since the days of Charles Darwin. But a new study is turning that belief on its head.

A team of researchers from the University of Texas at Austin examined the evolutionary changes in a tree lizard after the arrival of another, invasive tree lizard. The researchers found that not only did green anole lizards evolve, they did so quickly enough that the team could see the physical changes.

"When those red anoles moved in, the green anoles moved up [from their territory near the bottom of trees] quite quickly," says Yoel Stuart, the study's lead author to As It Happens host Carol Off. "Within a matter of months we found that they had moved two feet up into the trees, into the lower parts of the canopy and not where the branches and leaves are."

The invasive red anoles are larger than the native green species.

"We think that they moved up because they were just being out-competed down below," Stuart theorizes. "They weren't as strong as their competitors when they were closer to the ground so they moved up where there weren't any other lizards to interact with -- and there they were probably able to find more food and more space to hold their territory and just live."

In addition to moving from their species' habitat, the green anoles also evolved physically.

"The green lizards that moved up into the trees ended up evolving larger toe pads with more specialized scales on them. These scales have small hairs on them that allow them to cling to surfaces."