A new study led by Alex Gunderson with PhD student Julie Rej, published in the Journal of Thermal Biology, examined how temperature affects aggressive interactions between invasive brown anoles and native green anoles. The work, carried out at the Gunderson Lab with support from Tulane University, tested whether behavioral shifts under warming could change competitive outcomes between the two species that use the same habitat.
Rej measured aggression by placing pairs of brown and green anoles in controlled enclosures that simulated seasonal temperature ranges, from cool spring days to hotter summer conditions expected in the future. Across these trials, brown anoles consistently showed higher levels of aggression. While rising temperature increased aggression in both species to some degree, the increase was larger for brown anoles, widening the aggression gap as temperatures rose.
The authors note an earlier Tulane study that reported record-high lead levels in brown anoles collected in New Orleans, which raised questions about whether lead exposure could explain aggressive behaviour. Gunderson said the team cannot yet rule out a connection, but current evidence points elsewhere and they have not seen lead affecting the anoles in other ways. Their best-supported finding remains that aggression increases with warmer temperatures.
Overall, the study adds to evidence that behavioural responses to temperature are an important factor in future species interactions and competition as global temperatures rise, and that warming may further advantage invasive species in some cases. Source: Tulane University.
Difficult words
- invasive — species that arrive and spread in new areas
- aggression — hostile or threatening behaviour toward other animals
- enclosure — a fenced or controlled area for animalsenclosures
- exposure — contact with a harmful substance or condition
- evidence — information or data that supports a conclusion
- advantage — a condition that gives a benefit or edge
- competition — interaction where species compete for the same resources
- simulate — to copy conditions in a controlled experimentsimulated
Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.
Discussion questions
- How could increased aggression from invasive species change outcomes for native species in shared habitats?
- What additional experiments or data would help test whether lead exposure affects anole behaviour?
- If warming may advantage invasive species, what management steps could conservationists consider?
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