(University of California – Berkeley) A unique butterfly breeding experiment gave UC Berkeley researchers an opportunity to study the physical and genetic changes underlying the evolution of structural color, responsible for butterflies’ iridescent purples, blues and greens. Using helium ion microscopy, the scientists discovered that a 75% increase in thickness of the chitin lamina of wing scales turned iridescent gold to shiny blue. They showed that knocking out a gene called optix achieves the same result: a bluer Common Buckeye.

Original source: https://www.eurekalert.org/pub_releases/2020-04/uoc–wds040820.php