Aposematic patterns shift continuously throughout the life of poison frogs

Color and pattern are often dynamic traits that change throughout an individual's lifetime. Still, long-term shifts in coloration have received limited attention. Dendrobatid poison frogs are a classical system in the study of color and pattern evolution in which both sexual selection and predation avoidance are thought to drive the evolution of color and pattern at the population and species level. Here, we highlight an overlooked axis of pattern diversity, within individual variation, using three species in the genus Dendrobates. We collected longitudinal photographs of individuals at the National Aquarium to test the hypothesis that patterns shift predictably throughout the lifetimes of individual frogs. In all three species, we found a consistent reduction in the relative area of aposematic color as individuals aged and that the rate of pattern shift did not differ between the sexes. Consequently, within individual variation in coloration may confound inferences from ecological studies that inherently assume individual pattern is static. Finally, we note that using simple and noninvasive photography protocols, animals in zoos and aquaria have the potential to deepen our understanding of how color and pattern change throughout the lifetimes of a wide range of species.