Thriving in a hostile world: insights from the dietary strategy of two allopatric, closely-related tepui summit endemic amphibians

To date, there has been no published investigation on the trophic diversity in any tepui summit vertebrate. In this paper we analysed the dietary composition of a tepui summit endemic toad, Oreophrynella quelchii from Roraima-tepui, and compared it with that of O. nigra, to examine to what extent diet differs between these two sister species across isolated, although neighbouring, tepui tops. The digestive tracts of a total of 197 toads were dissected: 111 from O. quelchii  and 86 from O. nigra. The diet composition of O. quelchii was relatively diverse, with 13 major prey categories; mites (Acari, 36.5%) and beetles (Coleoptera, 21.0%) numerically dominated its diet. Despite occurring on two different tepui summits, O. quelchii and O. nigra exhibited a similar diet composition, although in O. nigra mites (Acari, 42.4%) and hymenopterans (especially ants, 16.9%) numerically dominated the diet. The present data suggest that tepui summit Oreophrynella species are flexible in their diet and are active foragers that also feed on aquatic arthropods, successful strategies in tepui competitive environments.