Human Footprint

Catching anoles is a delicate scientific process involving a fishing pole and some string.

Luckily, I came prepared, maybe a little too prepared.

Who comes out catching anoles in flip flops?

This is how you catch urban anoles.

You don't need those big boots.

You go out in your hiking boots and your field clothes, oh you're going to get a lot of looks.

You can dress casual, like you're going out on a little walk, even bring a little boombox with you.

That helps a lot because no one walks around doing sketchy stuff listening to reggaeton.

Got him first.

we measure with a digital x-ray the, all the bones in the body.

And you can see that they have these enlarged toe pads on the fore and the hind feet.

And so if you were to zoom way in on those, you'd be able to see these tiny scales and those let the lizards cling to the smooth surfaces.

So for the Puerto Rican crested and all, what did you find?

One of my initial findings was that in the city, the lizards had longer limbs relative to their body length.

Larger toe pads, with more of these specialized scales on the toe pads.

Okay.

These are exactly the kinds of adaptations you might expect to see in cities, based on what we already know about anoles living elsewhere.

They're clinging to things like glass and metal and even painted concrete, which is a lot smoother than anything you find in the forest.

And so there's kind of this combined selective pressure on toe pads, making them able to cling better and limb length, making them able to navigate the structure better.

Okay.

The urban lizards were different.

But the real test was whether they could actually outperform their forest dwelling counterparts when facing a uniquely urban challenge.

So I set up a lizard racetrack and I fitted the racetrack with different surfaces.

One was tree bark, one was metal like fence post metal, and then one was painted concrete.

And then I took high speed video of these lizards racing up the racetracks.

And what I found was or what I expected rather I should start there is that the urban lizards would be able to run faster on the concrete in the metal, and the urban substrates.

Those are the environments that they living at?

Yeah, exactly.

And so they'd be better at doing that than the forest lizards.

What I found, though, was that the urban lizards just faster overall.

On anything?

On anything.

Even like bark and stuff that's in forest?

Even bark, no matter what angle, no matter what structure we put on the track surface, they were faster.

Theyre just hot rods.

Mhmm.