Urban Lizards Evolving

Urban lizards are prevalent in Puerto Rico and the Carolina's. Many of them have taken to residing in urban areas due to deforestation and commercial tracts of shopping centers popping up along our highways.

City versus Forestal Anoles

One species of urban reptile, the anole has evolved stickier feet and longer legs to cling better to surfaces of glass, steel, wood and other construction materials used in urban areas.

In a recent scientific report, Kristin Winchell of the University of Massachusetts Boston and her research team compared male anole lizards living in the cities of Mayagüez, Ponce and San Juan in Puerto Rico with those residing in nearby forests. The research discovered that those residing in the urban areas had developed longer limbs and sticky feet that allow them to suction themselves to urban surfaces on homes, stores and business complexes.  

Compared with forest anoles, city lizards had longer limbs and more lamellae – scale-like structures that help their toes stick to these surfaces. These new features enabled them to stay attached to slippery urban perches as well. “I chased a lizard that ran straight up a window 30 feet and was out of reach in 15 seconds,” says Winchell. “I couldn’t catch this well-adapted lizard.”

Green versus Brown Anoles

In the Carolina's, there are both green and brown anoles. However, in a number of recent reports, the brown anole appears to be outnumbering the green, which might indicate that evolution is at play turning the green into brown lizards. This however is not accurate, but there are evolutionary triggers that are in play.

For the last decade, most of the anoles in the Carolina backyards were the little green natives. While they have the ability to change their color from green to brown, it's the invasive brown anoles, which are not chameleons that are gaining in population. The browns are the aggressive cannibals. They eat the eggs of their green cousins.

When brown anoles infringe on the green's territory, the latter take to the treetops and become scarcer.

Green anoles also adapt to their new situation by improving their speed, which makes adept tree climbers. From an evolutionary standpoint, scientists have discovered the green's foot pads have become larger, as a result of the browns forcing them into tree canopies. This change is said to be a case of rapid genetic adaptation going on before our eyes.

If you reside in the Carolina's or in Puerto Rico, keep an eye on these urban lizards and report back as to the evolutionary changes you are noticing. They're changing fast, so I'll be back in touch regarding what I'm learning as well.

Primary Source: Science Magazine