Invasive frogs show persistent physiological differences to elevation and acclimate to colder temperatures.

Area of Science:

• Ecology
• Physiology
• Invasive Species Biology

Background:

• The invasive coqui frog (Eleutherodactylus coqui) is expanding its range in Hawai'i.
• Concerns exist about its potential invasion of high-elevation habitats crucial for endemic species.

Purpose of the Study:

• To investigate if coqui frog thermal tolerance and physiology change along Hawai'i's elevational gradients.
• To determine the coqui frog's capacity for thermal acclimation.

Main Methods:

• Collected coqui frogs from low, medium, and high elevations in Hawai'i.
• Conducted short-term and long-term experiments to assess thermal tolerance and physiological responses.
• Measured critical thermal minimum (CTmin), blood glucose, oxidative stress, and corticosterone levels.

Main Results:

• Coqui frogs exhibited lower CTmin at higher elevations after short acclimation, showing local adaptation.
• After extended acclimation, CTmin decreased in cold-acclimated frogs, irrespective of origin elevation.
• Blood glucose levels correlated positively with elevation, while oxidative stress was higher in females.

Conclusions:

• Coqui frogs demonstrate significant thermal plasticity, acclimating to colder temperatures within weeks.
• This acclimation ability suggests potential for coqui frog expansion into higher elevation habitats.
• Elevational range expansion may be less restricted by cold temperatures than previously assumed.