Russell Gray, Catharina Karlsson

Biofluorescent animals have become a recent trend in natural history publishing. While the functions and origins of biofluorescence in fauna remains somewhat controversial, trends in biofluorescence throughout published literature may elucidate these concepts. Here we review 101 years of biofluorescent studies encompassing 108 published papers and 977 unique species records. Our results provide insights into areas of improvement that should be made moving forward in biofluorescent studies and hypotheses to be tested. Collated records of biofluorescent indicate that fluorescence is strongly associated with nocturnal and arboreal lifestyles. Our reconstruction of ancestral lineages based on biofluorescent species records indicate a potential origins and trends in evolution of biofluorescence around the Middle Miocene Climate Optimum (MMCO) where fluorescent color diversity proliferates with declining global temperatures and could possibly be indicative of a widespread climate relict among modern taxa; we therefore term this new concept the Biofluorescent Climate Relict Hypothesis (BCRH).