TY - JOUR T1 - Ultraviolet and yellow reflectance but not fluorescence is important for visual discrimination of conspecifics by <em>Heliconius erato</em> JF - bioRxiv DO - 10.1101/088781 SP - 088781 AU - Susan D. Finkbeiner AU - Dmitry A. Fishman AU - Daniel Osorio AU - Adriana D. Briscoe Y1 - 2016/01/01 UR - http://biorxiv.org/content/early/2016/11/20/088781.abstract N2 - Toxic Heliconius butterflies have yellow hindwing bars that – unlike their closest relatives – reflect ultraviolet (UV) and long wavelength light, and also fluoresce. The pigment in the yellow scales is 3-hydroxy-DL-kynurenine (3-OHK), found also in the hair and scales of a variety of animals. In other butterflies including pierids, which similarly display wing colors that vary in both the UV and the human-visible range, behavioral experiments have indicated that only the UV component is most relevant to mate choice. Whether in Heliconius butterflies it is the UV, the human-visible yellow, and/or the fluorescent component of yellow wing coloration that is relevant to mate choice is unknown. In field studies with butterfly paper models we show that both UV and 3-OHK yellow act as signals for H. erato but attack rates by birds do not differ significantly between the models. Furthermore, measurement of the quantum yield and reflectance spectra of 3-OHK indicates that fluorescence does not contribute to the visual signal under broad-spectrum illumination. Our results suggest that the use of 3-OHK pigmentation instead of ancestral yellow was driven by sexual selection rather than predation.Summary statement Heliconius butterflies use a co-opted yellow pigment for communication, while predators are fooled by non-Heliconius mimics using ancestral yellow pigments. ER -