Evidence for ecological tuning of novel anuran biofluorescent signals

Abstract

Our study assesses the variability of amphibian biofluorescence and provides insight into its potential functions and role in anuran evolution. Via a field survey across South America, we discovered and documented patterns of biofluorescence in tropical amphibians. We more than tripled the number of species that have been tested for this trait and added representatives from previously untested anuran families. We found evidence for ecological tuning (i.e., the specific adaptation of a signal to the environment in which it is received) of the novel anuran biofluorescent signals. Across groups, the fluorescence excitation peak matches the wavelengths most available at twilight, the light environment in which most frog species are active. Additionally, biofluorescence emission spans both wavelengths of low availability in twilight and the peak sensitivity of green-sensitive rods in the anuran eye, likely increasing contrast of this signal for a conspecific receiver. With evidence of tuning to the ecology and sensory systems of frogs, our results suggest frog biofluorescence is likely functioning in anuran communication.