@article {Finkbeiner088781, author = {Susan D. Finkbeiner and Dmitry A. Fishman and Daniel Osorio and Adriana D. Briscoe}, title = {Ultraviolet and yellow reflectance but not fluorescence is important for visual discrimination of conspecifics by Heliconius erato}, elocation-id = {088781}, year = {2016}, doi = {10.1101/088781}, publisher = {Cold Spring Harbor Laboratory}, abstract = {Toxic Heliconius butterflies have yellow hindwing bars that {\textendash} unlike their closest relatives {\textendash} 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.}, URL = {https://www.biorxiv.org/content/early/2016/11/20/088781}, eprint = {https://www.biorxiv.org/content/early/2016/11/20/088781.full.pdf}, journal = {bioRxiv} }