Modern Caterpillars Evolved Due to Climate Change

It turns out that climate change is having a drastic impact on some species of the insect world. Researchers have found that caterpillars of two species of butterflies in Colorado and California have evolved to feed rapidly at higher and at a broader range of temperatures in the past 40 years. This suggests that the insects are evolving quickly in order to cope with a hotter, more variable climate.

"To our knowledge, this is the first instance where we show changes in physiological traits in response to recent climate change," said Joel Kingsolver, one of the researchers, in a news release.

Caterpillars can only eat and grow when it's not too cold and not too hot. When temperatures are ideal, though, these insects devour plant material with reckless abandon. In fact, they can gain up to 20 percent of their body weight in an hour. This growth in particular is what determines whether or not these caterpillars survive, when they turn into adult butterflies and their ultimate reproductive success.

In order to examine these caterpillars a bit more closely, the researchers compared modern caterpillars to their ancestors from 40 years ago. In the end, they found that two related species of Colias butterflies have adapted by broadening the range of ideal feeding temperatures and shifting their optimal feeding temperature to a higher one.

"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 Jessica Higgins, one of the researchers, in a news release. "Our climate is changing. The thermal physiology of these species is changing, too."

The findings reveal how these species can adapt and change in order to respond to a warmer world. It's important to note exactly which species are more adept at evolving and which may be suffering from climate change, unable to cope in time.

The findings are published in the journal Functional Ecology.