Urban Lizards Show 'Evolution as It's Unfolding'

'Anolis cristatellus' evolved to cling to windows and walls over 30 to 80 generations: study
By Newser Editors and Wire Services
Posted Jan 15, 2023 2:10 PM CST
Urban Lizards Show 'Evolution as It's Unfolding'
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)

Lizards that once dwelled in forests but now slink around urban areas have genetically morphed to survive life in the city, researchers have found, per the AP. The Puerto Rican crested anole, a brown lizard with a bright orange throat fan, has sprouted special scales to better cling to smooth surfaces like walls and windows and grown larger limbs to sprint across open areas like parking lots, scientists say. "We are watching evolution as it's unfolding," said Kristin Winchell, a biology professor at New York University and main author of the study in the Proceedings of the National Academy of Sciences.

As urbanization intensifies around the world, it's important to understand how organisms adapt and humans can design cities in ways that support all species, Winchell said. The study analyzed 96 Anolis cristatellus lizards, comparing the genetic makeup of forest-dwellers to those living in Puerto Rico's capital, San Juan, as well as the northern city of Arecibo and western city of Mayaguez. Scientists found that 33 genes within the lizard genome were repeatedly associated with urbanization. "You can hardly get closer to a smoking gun!" said Wouter Halfwerk, an evolutionary ecologist and professor at Vrije University Amsterdam who was not involved in the study but has previously shown that one frog species changed its mating call in urban areas.

Winchell said the lizards' physical differences appeared to be mirrored at the genomic level. "If urban populations are evolving with parallel physical and genomic changes, we may even be able to predict how populations will respond to urbanization just by looking at genetic markers," she said. The changes in these lizards, whose lifespans are roughly 7 years, can occur very quickly, within 30 to 80 generations, enabling them to escape from predators and survive in urban areas, Winchell added. The study focused on adult male lizards, so it's unclear if females are changing in the same way or at the same rate as males, and at which point in a lizard’s life the changes are occurring. (Read more evolution stories.)

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