Butterfly experts have suspected for more than 150 years that vision plays a key role in explaining wing color diversity. Now, for the first time, research led by UC Irvine biologists proves this theory true – at least in nine Heliconius species. Butterflies that have a duplicate gene allowing them to see ultraviolet colors also have UV-yellow pigment on their wings, reports the study by UCI’s Adriana Briscoe, Seth Bybee and colleagues. The UV-yellow pigment may help the butterflies survive by facilitating the search for appropriate mates, which leaves more time for reproducing, eating and thriving. They’re not wasting their time chasing after the wrong mate, says Briscoe, associate professor of ecology & evolutionary biology and lead author of the study, published online recently in the Proceedings of the National Academy of Sciences.