Aposematic patterns shift continuously through 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 pattern shifts 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.