It’s no mystery that temperature affects nearly all biological processes. That includes acoustic signals emitting out and reception.
It’s a particular hazard for critters who rely on sound for mating calls like frogs. And because frogs are ectotherms–cold-blooded organisms—they’re often considered harbingers of major changes in the climate.
In a study released by the Proceedings of Royal Society Biological Sciences, researchers found that the coqui, a Puerto Rico brown frog, has changed its pitch over the last two decades, a correlation it noted with a rise in temperature.
This change in vocalization for the coqui could, the researchers warned, have dire consequences. With the shorter and higher pitched calls the frog now gives, that may affects its body size, shrinking the frog, and that could have ramifications across the food chain.
The mating calls on the Puerto Rican coqui frog were compared to similar recordings made 23 years ago. All of the observed differences are consistent with a shift to higher elevations for the population, a well-known strategy for adapting to a rise in ambient temperature.
Using independent temperature data over the same time period, the researchers noted a significant increase in temperature, the magnitude of which closely predicts the observed changes in the frogs’ calls. And the shorter and higher pitched the male coqui frogs calls have now have been linked to their smaller body size.
Temperature influences a coqui frog’s body size, and researchers think their size is key to the frequency of their calls and the pitch sensitivity of their inner ear.