RT Journal Article SR Electronic T1 Ultraviolet and yellow reflectance but not fluorescence is important for visual discrimination of conspecifics by Heliconius erato JF bioRxiv FD Cold Spring Harbor Laboratory SP 088781 DO 10.1101/088781 A1 Susan D. Finkbeiner A1 Dmitry A. Fishman A1 Daniel Osorio A1 Adriana D. Briscoe YR 2016 UL http://biorxiv.org/content/early/2016/11/20/088781.abstract AB 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.