Butterfly Eyespots Reveal How Evolution Works with New Traits

Scientists are learning a bit more about evolution, thanks to the colorful patterns on butterfly wings. Researchers have taken a closer look at the "eyespots" on certain butterflies in order to answer some fundamental questions about evolution.

In this particular case, the researchers wanted to explain the existence of what are called "serial homologues," which are patterns in nature that are repetitive, serve a function, and are important enough that they're retained through millions of years across vast numbers of species. A few examples of some of these features would be repeated vertebrae that form a spinal column and rows and rows of teeth. Yet another one of these features, though, are the eyespots on butterfly wings.

Eyespots can serve as markings for both predator avoidance and mate identification. One theory holds that these spots evolved from simpler, single spots while a second theory states that they evolved from a "band" of color which later separated into spots. Yet it turns out that neither of these theories are correct.

"At first, it appears the eyespots helped this group of butterflies with one of the most basic aspects of survival value, which is avoiding predators," said Jeffrey Oliver, one of the researchers, in a news release.

In fact, the researchers found that the spots are the result of a genetic mutation and acquired a function that had evolutionary value. The eyespots acted as camouflage from a distance and then acted as a "bullseye" for predators when they were close; though when they were close, it directed predators to the tips of the less-important wings rather than toward the head or body of the insect.

"If you take this same concept and apply it to other important features like vertebra and a spinal column, it suggests that some small number of bones would form through mutation, and eventually move, join and be perpetuated as the acquired a function with survival value," said Oliver in a news release. "There would be a biological position in which they were supposed to form, and that would be retained. And over time, the vertebra might expand in number, and acquire other functions that had nothing to do with their original function, but which still had value."

The findings are published in the journal Proceedings of the Royal Society B: Biological Sciences.