Invasive brown anoles⁣ (Anolis sagrei) are exhibiting increased aggression towards native green anoles (Anolis carolinensis) as temperatures climb, according to a new study published in ⁢the
Journal of ⁤Thermal Biology.This shift in behavior suggests that warming conditions could considerably alter the competitive dynamics⁢ between the ⁤two lizard species, perhaps favoring the invasive brown anole.

The research builds upon previous work from Tulane University that documented surprisingly high levels of lead in brown anoles inhabiting new Orleans,as reported by Futurity. Initial speculation centered on whether lead exposure might be contributing to the brown anoles’ assertive behavior. However, the current study indicates that temperature is a more likely driver of this increased aggression.

What the ⁣Study Found

Researchers conducted experiments exposing both brown and green‍ anoles to varying temperatures. They observed that as temperatures increased, brown anoles displayed more frequent and intense aggressive behaviors-including head-bobbing displays, chasing, and biting-towards green anoles. This heightened aggression was particularly noticeable at temperatures exceeding 30°C (86°F).

“We found a clear correlation between temperature and aggression,” explains Alex Gunderson, assistant professor of ecology and evolutionary biology at Tulane University and senior author of the study. “The warmer it gets, the more likely brown anoles are to challenge and displace green anoles.”

Why This⁣ Matters: The‍ Competitive Balance

The green anole is native to the southeastern United⁣ states,while ⁢the brown anole is⁣ an invasive species originating from Cuba and the Bahamas. Introduced to the U.S. in the 1950s, brown anoles have rapidly expanded their ‍range, often outcompeting native anole populations.

The increased aggression observed ⁣in the study suggests that climate change could exacerbate this competitive imbalance. As temperatures continue to rise due to global warming,⁣ brown ⁤anoles may gain an even greater advantage, potentially leading to further declines in green anole populations. This is particularly concerning given the ecological role green anoles play as insectivores.

Lead Exposure: Still a Question?

While the current study points⁢ to temperature as the primary driver of increased aggression,⁤ researchers haven’t entirely dismissed the possibility that lead exposure could play a contributing role. ⁣The previous Tulane research revealed that brown anoles in New Orleans have developed