Sea as a color palette: the ecology and evolution of fluorescence

Fluorescence and luminescence are widespread optical phenomena exhibited by organisms living in terrestrial and aquatic environments. While many underlying mechanistic features have been identified and characterized at the molecular and cellular levels, much less is known about the ecology and evolution of these forms of bioluminescence. In this review, we summarize recent findings in the evolutionary history and ecological functions of fluorescent proteins (FP) and pigments. Evidence for green fluorescent protein (GFP) orthologs in cephalochordates and non-GFP fluorescent proteins in vertebrates suggests unexplored evolutionary scenarios that favor multiple independent origins of fluorescence across metazoan lineages. Several context-dependent behavioral and physiological roles have been attributed to fluorescent proteins, ranging from communication and predation to UV protection. However, rigorous functional and mechanistic studies are needed to shed light on the ecological functions and control mechanisms of fluorescence.