I have to confess that I was not particularly enthusiastic about opening up this thread. The title left me a little cold. But when I read the article you linked to, I was QUITE interested!!!
Here's a summary from the article:
"After contact with the invasive species [from another island], the native [Florida] lizards began perching higher in trees, and, generation after generation, their feet evolved to become better at gripping the thinner, smoother branches found higher up."
"The change occurred at an astonishing pace: Within a few months, native lizards had begun shifting to higher perches, and over the course of 15 years and 20 generations, their toe pads had become larger, with more sticky scales on their feet."
I found this fascinating! Why? Because this short article covers the two intersecting forces that we usually call "Natural Selection" !
Here is the conclusion in a nutshell:
"Stuart also noted that the adults of both species are known to eat the hatchlings of the other species. '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. '... if you have bigger toe pads, you'll do that better than if you don't.' "
Apparently the invading species was better at eating hatchlings of the native species than vice versa (otherwise, we would have found a change in invading species) - - assuming of course, the invading species doesn't already have optimum toe pads!
As the old joke goes, when a bear is charging you and your friend in the woods, you don't have to outrun the bear ... you just need to outrun your friend!
Any inadequately "toe-padded" lizard either perished by being the last ones to get away from the invading mauraders ... or were the least able to prosper at the higher levels. The combined effect concentrated the "bigger toe pad" alleles into a smaller population - - where the smaller populations become more responsive to pressures from natural selection!