A team led by Alex Gunderson with PhD student Julie Rej studied how warming affects aggression between invasive brown anoles and native green anoles. The research, done at the Gunderson Lab and supported by Tulane University, appears in the Journal of Thermal Biology. The team wanted to know if behaviour changes with temperature could alter competition between the species.
To measure aggression, Rej placed pairs of brown and green anoles together in controlled enclosures that simulated seasonal temperature ranges. Across these tests, brown anoles showed higher aggression than green anoles. Rising temperature increased aggression in both species, but the increase was larger for brown anoles, so the gap in aggression widened as it got warmer.
The authors say these results indicate that climate warming could tip the competitive balance further in favor of the invasive species. They note that heat-driven aggression may help explain some cases where brown anoles displace green anoles in the wild.
Difficult words
- invasive — A species that spreads into new areas
- native — Living naturally in a particular area
- aggression — Hostile or angry behaviour toward others
- competition — When animals fight for the same resource
- simulate — To copy or create similar conditions artificiallysimulated
- enclosure — A closed area used to keep animals insideenclosures
- displace — To force out or replace from a place
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Discussion questions
- Have you seen an example of an invasive species where you live? How did it affect native species?
- What actions could scientists or local communities take to help native anoles if warming increases aggression?
- Do you think experiments in controlled enclosures give useful information about what happens in nature? Why or why not?
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