Feeding or avoiding? Facultative egg feeding in a Peruvian poison frog (Ranitomeya variabilis)

The choice of breeding resources can be very important for the reproductive success and accordingly the fitness of an individual. Often, however, advantageous breeding sites also include disadvantageous characteristics. Neotropical poison frogs (Dendrobatidae), for example, use phytotelmata for the deposition of their tadpoles. The exploitation of these small pools is advantageous as it lowers the risk of predation, but it is also costly because of limited resource availability. Several species evolved regular provision with unfertilized trophic eggs to compensate for the resource limitations for their tadpoles. Fertilized eggs in contrast are usually deposited outside of the phytotelmata in both egg-feeding and non-feeding species, to avoid consumption by cannibalistic conspecific tadpoles. The Peruvian species Ranitomeya variabilis is an exception: clutches are deposited within the phytotelmata. Several studies show a strong avoidance for egg deposition within phytotelmata already containing a tadpole. Here the hypothesis is tested that this avoidance behavior is mainly directed towards unrelated offspring, while R. variabilis is less concerned and therefore shows less avoidance when faced with its own offspring. Therefore, two setups were compared, one in which frogs had to face newly erected phytotelmata containing cues of non-familiar tadpoles and one where phytotelmata remained at the same place, so frogs could deposit and recognize their own tadpoles. While non-familiar tadpoles were completely avoided for egg deposition, phytotelmata with familiar tadpoles received several clutches, suggesting a form of parental care in R. variabilis that exceeds the transportation of tadpoles and might be a step towards egg feeding.