Anomalous tadpoles in a Brazilian oceanic archipelago: implications of oral anomalies on foraging behaviour, food intake and metamorphosis Herpetological Society

Rhinella jimi (Anura, Bufonidae) is an introduced species in the archipelago of Fernando de Noronha, north-eastern Brazil. It is known as one of the greatest amphibian anomaly hotspots in the world, with almost half of the adult individuals in the population having external anomalies, but tadpoles from this population have not previously been examined. Therefore, we evaluated the presence of anomalies in tadpoles of this population, described their types and identified possible handicaps of anomalous tadpoles in foraging behaviour and food intake. We found anomalies in 52.5% of all tadpoles inspected, mostly involving labial teeth. Anomalous tadpoles, when compared to normal individuals, spend less time foraging and have a lower foraging efficiency. We also observed that anomalous toadlets originate both from normal and anomalous tadpoles. We suggest that the reduced feeding fitness may result in a reduced growing rate, longer time spent until metamorphosis, higher predation risk, different body mass, size and morphology in metamorphs and adults. However, this apparent handicap may not affect the post-metamorphic population, as anomalous adults may rise from normal tadpoles.