An ongoing research collaboration between Adriana Briscoe, from the Ecology and Evolutionary Biology Department at UC Irvine, and Jorge Llorente Bousquets, from the Evolutionary Biology Department at UNAM's Facultad de Ciencias, explores the evolution of butterfly color vision and wing color as a mode of communication and signaling within a species and also among mimic species and predators. Their research was supported in its pilot phase by a 2008 UC MEXUS-CONACYT collaborative grant and now includes the work of Seth M. Bybee (UC Irvine; Brigham Young University), Furong Yuan (UC Irvine), Monica D. Ramstetter (UC Irvine), Robert D. Reed (UC Irvine), Daniel Osorio (University of Sussex, U.K.), and Claudia Hernández Mejía (UNAM). The team's investigation of toxic Heliconius or passionvine butterflies and their mimics from tropical America reveals that a predator's vision is not as effective as Heliconius butterfly vision in discriminating between Heliconius ultraviolet-reflecting yellow wing colors and the yellow wing colors found in Heliconius' mimics.
The research team discovered that some Heliconius have two ultraviolet opsin genes, whereas most butterfly species have one. Opsins are part of the visual pigments that allow animals to see. The gene duplication allows Heliconius to discriminate ultraviolet colors better and distinguish individuals of their own species from those of mimics. The team also found that the gene duplication appears to have evolved in tandem with other genetic changes producing ultraviolet-yellow wing pigments. Birds, which are major predators of butterflies, have one ultraviolet visual-pigment and are much less well-equipped to separate Heliconius species from their mimics. The enhanced ultraviolet-vision together with the ultraviolet-yellow wing pigments may allow poisonous Heliconius butterflies a private communication channel for members of their own species, while still allowing mimic butterfly species to fool their predators.
The long-term project has received additional funding from NSF, CONACYT, CONABIO, and DGAPA-UNAM and the findings reported in the Proceedings of the National Academy of Sciences U.S.A (2010) and The American Naturalist (2012). For additional information and publication references, please consult Dr. Briscoe's or Dr. Llorente Bousquet's web pages or their collaborative grant page.