Modern Caterpillars have Rapidly Evolved to Feed Faster due to Climate Change

A modern species of caterpillars is evolving at a much faster rate in response to higher temperatures from climate change. Researchers believe that warmer weather in the past 40 years may explain the reason that these creatures feed rapidly in order to survive.

"To our knowledge, this is the first instance where we show changes in physiological traits in response to recent climate change," said lead study author Joel Kingsolver at the University of North Carolina at Chapel Hill, via a press release. 

Background information from the study notes that caterpillars are known to only eat and grow in cold temperatures. However, when temperatures are not ideal, they gorge and gain up to 20 percent of their body weight in under an hour. This growth helps them survive in unfavorable environmental conditions and may explain how quickly adult butterflies can still reproduce successfully.

Jessica Higgins, a graduate student in Kingsolver's lab who spearheaded the study, worked with fellow graduate student Heidi MacLean, Lauren Buckley, currently at the University of Washington, and Kingsolver to compare modern caterpillars to their ancestors from 40 years ago. Their results show that the two related species of Colias (sulphur) butterflies have adapted in two ways, courtesy of the release.

• broadened the range of ideal feeding temperatures
• shifted their optimal feeding temperature to a higher one

The researchers measured climate changes at the two study sites and then examined changes in the caterpillars feeding rates by using both current and historical data from the 1970s, collected by a graduate advisor.

Though they found little change in average air temperature at bothy study sites, researchers noted how frequencies of hot temperatures (or those above 82 degrees Fahrenheit) increased two-fold in Colorado and four-fold in California over the past 40 years.

Due to the climate change, modern caterpillars in Colorado ate faster in higher temperatures than those living in the same region during the 1970s. Modern-day caterpillars found in California ate faster at both past and current environments. However, researchers note that their optimal temperature-range did not change. 

"These two species of caterpillars adapted to the increased frequency of higher temperatures over 40 years in two different ways, but both are better suited than their ancestors to thrive in a hotter, more variable climate," said Higgins, via the release. "Our climate is changing. The thermal physiology of these species is changing, too."

More information regarding the study can be found via the journal Functional Ecology.