Researchers have found the genetic components responsible for producing different patterns of color on butterfly wings and discovered that these were shared between species millions of years ago, a "genetic paint box" shaken up to create a wide range of wing displays.
Two of the most common patterns of color found on Amazonian Heliconius butterflies — the ray red streaks fanning out across the back wing and the dennis red patch across the forewing's base — were shown to be under the control of separate genetic switches, which originated from completely different species.
The researchers traced when the wing patterns merged to manifest in the Amazonian Heliconius and found interbreeding evidence from nearly 2 million years ago.
Exchanging genes is crucial to evolution and, in butterflies; swapping wing patterns with different species became a way to escape predators. However, the study, published in PLOS Biology, was the first to document the mixing of genetic material that led to entirely new wing patterns.
For the study, the researchers sequenced genomes from 142 individual butterflies from 17 species of Heliconius, comparing DNA data focused on parts of the butterfly associated with the two common wing patterns.
"In each butterfly genome, we narrowed down around 300 million base pairs of DNA to just a few thousand," said Chris Jiggins, the study's senior author.
The researchers saw that while the genetic switches for the wing patterns were situated next to each other, they operate independently. Sequencing showed that the switch for every color splotch only evolved once in separate species, but it was shared repeatedly across Heliconius species at interbreeding points.
With the identification of the genetic switches related to wing patterns in the butterfly, the researchers will now be able to map out the species tree and show how the color patterns jumped from one species to another.
Other authors for the study include: Richard W. R. Wallbank, W. Owen McMillan, Simon W. Baxter, Nicola Nadeau, Carolina Pardo-Diaz, Mathieu Joron, Joseph J. Hanly, Camilo Salazar, Simon H. Martin, Kanchon K. Dasmahapatra and James Mallet. It received funding support from the European Research Council and the Biotechnology and Biological Sciences Research Council.
Photo: Thomas Bresson | Flickr
