Crested Anole Lizard Adapts To Urban Life

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Researchers have found that lizards that once lived in forests but now inhabit cities have genetically modified to survive urban life.

The Puerto Rican crested anole, a brown lizard with a bright orange throat fan, has evolved specialized scales to better cling to smooth surfaces like walls and windows, and grown larger limbs to sprint across open spaces, according to scientists.

“We’re watching the development as it unfolds,” said Kristin Winchell, a New York University biology professor and lead author of the study, which was published Monday in the Proceedings of the National Academy of Sciences.

As cities grow around the world, it’s important to understand how creatures can adapt and how people can shape cities to support all species, Winchell said.

The study analyzed 96 anole crested lizards (pronounced uh-NOLES or uh-NO-leez) and compared the genetic makeup of forest dwellers to those living in San Juan, Puerto Rico’s capital, as well as the northern and western cities of Arecibo City of Mayaguez.

Scientists found that 33 genes within the lizard genome were repeatedly linked to urbanization as a place becomes a larger city.

“You can’t get any closer to a smoking gun!” said Wouter Halfwerk, an evolutionary ecologist and professor at Vrije University Amsterdam who was not involved in the study.

The changes in these lizards, which have a lifespan of about seven years, can occur very rapidly, in 30 to 80 generations, allowing them to escape predators and survive in urban areas, Winchell added. For example, the larger limbs help them run faster across a hot parking lot, and the specialized scales grip onto surfaces much smoother than trees.

The scientists hunted down dozens of lizards for their study, catching them with their hands or using fishing rods with a tiny lasso to catch them. “It takes some practice,” Winchell said. Occasionally they had to ask permission to catch lizards outside people’s homes.

One of Winchell’s favorite finds was a rare albino lizard. She also found one nearly eight inches tall, quite large for the species, which she named “Godzilla.”

The study focused on adult male lizards, so it’s unclear whether females change in the same way or at the same rate as males, and at what point in a lizard’s life the changes occur.