Alkaloid avoidance in poison frog tadpoles

Abstract

Animals show a spectrum of avoidance-tolerance to foods containing toxic secondary metabolites. However, this spectrum has not been evaluated in animals that may actively seek out these compounds as a chemical defense. Poison frogs sequester toxic and unpalatable alkaloids from their diet, and in some species, tadpoles are exposed to these toxins before the development of their skin granular glands, which are used for toxin compartmentalization. Here, we examined the effects of the alkaloid decahydroquinoline (DHQ) in tadpoles of the Mimetic poison frog, Ranitomeya imitator, using alkaloid supplemented food. We found that although their survival is lowered by the alkaloid, their development is only mildly affected, with no evident effects on their growth. Furthermore, locomotor activity and feeding behavior was altered in the first week of DHQ treatment, probably in part through nicotinic blockade. However, after two weeks, tadpoles learned to avoid the alkaloid by visiting the food area only when necessary to eat. Our results suggest that poison frogs navigate the avoidance-tolerance spectrum during the development of their sequestration machinery. SummaryAnimals avoid consuming toxic foods or have anti-toxin machinery to avoid food poisoning. Adult poison frogs eat toxic insects and store the toxins in their skin glands. Some poison frog species even feed their tadpoles with toxins to protect them from predation at the risk of poisoning them. In this study, we observed that toxic food did not affect the development of tadpoles because they quickly learned to eat just enough to grow without getting poisoned. Our results indicate that poison frogs use diverse ways to avoid food poisoning during development.