< Study: Lizard Changed Genetically to Survive in the City
By Bryan Lynn
16 January 2023

A new study has found that a lizard that once lived in forests has gone through genetic changes to survive in city environments.

Researchers studied a lizard called the crested anole. The lizard's official name is Anolis cristatellus. It is commonly found in the American territory of Puerto Rico.

The team said it discovered the lizard had grown special scales that helped it climb more easily on smooth surfaces like walls and windows. It also grew longer legs in order to run faster across open areas.

In this photo courtesy of evolutionary biologist Kristin Winchell, an Anolis cristatellus lizard stands on a gate in Rincon, Puerto Rico, Jan. 6, 2018. (Kristin Winchell/New York University via AP)
In this photo courtesy of evolutionary biologist Kristin Winchell, an Anolis cristatellus lizard stands on a gate in Rincon, Puerto Rico, Jan. 6, 2018. (Kristin Winchell/New York University via AP)

Kristin Winchell is a biology professor at New York University and the main writer of the study. She told The Associated Press, "We are watching evolution as it's unfolding."

Research results were recently published in Proceedings of the National Academy of Sciences.

Winchell said as city development spreads out around the world, it is important to understand how organisms adapt to new environments. That way, she added, humans can design cities in ways that can support all kinds of animals.

The study examined 96 Anolis cristatellus lizards. Researchers compared the genetic makeup of lizards in forests to those living in Puerto Rico's capital, San Juan, as well as two other cities. Scientists found that 33 genes were repeatedly linked to city spread.

Wouter Halfwerk is an evolutionary ecologist and professor at Vrije University Amsterdam. He was not involved in the study. He told the AP, "You can hardly get closer to a smoking gun," meaning evidence or proof of something.

Halfwerk said he was excited that the researchers were able to identify such rich evidence that the lizards had changed genetically to adapt to a different environment.

Winchell said the research demonstrated that scientists might be able to predict how populations will react to city environments just by looking at genetic signs.

The study found that larger legs permitted the lizards to run more quickly across open city areas. And the special scales they developed permit them to hold onto surfaces that are much smoother than trees.

The scientists followed many lizards for the study, using their hands or fishing poles to catch them. "It takes some practice," Winchell said.

Among Winchell's favorite findings was a rare albino lizard. She also found a nearly 20-centimeter-long one, a rather large individual for that species of lizard. She decided to call that one "Godzilla."

The study centered on adult male lizards, so it is unclear if females are changing in the same way or at the same rate as males. The researchers said it is also not clear at which point in a lizard's life the changes happen.

Halfwerk's own research showed how one frog species changed its reproducing call in city areas. He said scientists should look next for possible limitations on evolutionary changes and how genetic adaptations relate to reproductive behavior.

Halfwerk added that for the adaptive changes to be lasting, "they need to lead to higher reproduction."

I'm Bryan Lynn.

The Associated Press reported this story. Bryan Lynn adapted the report for VOA Learning English.


Words in This Story

scale - n. a flat piece of hard material that covers the skin of some animals

evolution – n. the way in which living things change and develop over millions of years

adapt – v. to change something so that it is suitable for a different use or situation

smoking gun – n. information that proves something is true

practice – n. the act of doing something regularly in order to improve one's skills

species – n. a group of animals or plants that are similar and can produce young animals or plants

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