Ecological and metabolic traits of non-aposematic species challenge the crypsis-aposematic duality of Neotropical poison frogs

Within the context of animal defence strategies, most species are believed to be either cryptic or aposematic. In this sense, dendrobatid frogs are among the best-studied vertebrate systems in terms of colouration, behaviour, and chemical defence. Though a dual criterium, cryptic-palatable and conspicuous-toxic, was used to classify species within this clade, there are notorious exceptions that do not fit into this duality. In particular, some species assigned to the cryptic-palatable category possess colourful spots that markedly contrast the rest of the body's dark coloration and contain toxic substances. Here, we investigate whether two pairs of syntopic dendrobatids, in which one of the members within each pair has colour spots and the other a homogeneous dark colour, differ in the activity pattern, dietary specialization, foraging activity, and metabolic rate. In agreement with our prediction, we found that the coloured species in one of the pairs is more active and has a higher dietary selectivity and prey accumulation capacity. However, no association was not found for the other species pair. Furthermore, contrary to our prediction, species with coloured spots have a lower metabolic rate than their syntopic homogenous peers. Overall, our findings suggest that species with coloured spots could be classified in a different category based on ecological and metabolic traits while opening exciting perspectives for understanding the evolution of aposematism in amphibians.