Shifts in anoles’ skin color signal their health and vitality, research reveals

Aquatic anoles are remarkable creatures. Perched along the banks of steep waterfalls in the forests of Panama and Costa Rica, they are often seen leaning and peering into the rushing streams below, as if daring to leap. They could, if they wanted to. With a natural diving ability that allows them to stay submerged for minutes, these lizards have long fascinated scientists. But new research reveals another, more subtle secret: Changes in skin color quietly signal health and vitality.

Kelly Wuthrich, a Ph.D. biology student in Christian Cox’s lab at the FIU Environment Institute, decodes this secret language of color change, focusing particularly on female water anoles (Aquatic Anoles). Beneath the dense green canopies and towering trees of the Costa Rican jungle, she sought to discover meaning beyond camouflage, a common tactic used by lizards to hide from predators.

Its findings, recently published in the Biological Journal of the Linnaean Societyreveal that females in better physical condition have more blue and less green lateral stripes. These hues may attract potential mates, but they could also reflect the health of the ecosystem, hinting at the environmental changes that shape the species.

“People just assume that females have dull coloration and don’t use their signals to attract males or for any sort of communication,” Wuthrich said. “But that may not be true.”

Through these delicate changes, females could communicate their general condition, signaling their fitness and willingness to reproduce. This glow, however, is fleeting and quickly fades under stress, whether due to poor diet, environmental pressures, encounters with predators, or the intense energy demands of egg production.

“If environments change, it can alter their ability to blend into their surroundings, making them more vulnerable to predators or even humans,” Wuthrich said.

For her, tracking the evolution of female water anoles offers a deeper understanding of how biology works and how the world itself evolves.

“Historically, men have dominated the field and been the subject of much study,” Wuthrich said. “I think it’s important to fully understand the extent to which females can play with their own signaling, even if it’s not as conspicuous as that of males.”

Could color changes also play a role in female-female communication? That’s what Wuthrich hopes to explore next. She wants to understand how female anoles interact with each other and what that might reveal about the genus as a whole. With more than 400 species distributed across Central and South America, the Caribbean and the United States, these findings could have far-reaching implications.

“This would give us insight into the evolution of this species itself,” Wuthrich said. “And that’s important. It’s important to understand our natural world. It’s where we live, where we come from, and we’re all distantly related to each other, even plants.”

Wuthrich would like to return to Costa Rica in search of the elusive females, determined to uncover the subtle signals that have until now remained largely unnoticed.