Como a vulnerabilidade à predação varia ao longo da ontogenia de girinos?

Abstract

During development, amphibian larvae (tadpoles) go through changes that modify their individual abilities. While sensory and cognitive abilities are predicted to develop progressively, the locomotor abilities would be lower in initial and later stages. Thus, the development of escape ability can depend on decoupled skills in these organisms. Here we experimentally investigated how vulnerability to predation varies throughout tadpole ontogeny in nurse frogs facing giant water bug larvae as predators. Based on sensory and cognitive abilities, we tested the hypothesis that the most vulnerable phases are the initial ones, expecting a linear relationship. Based on locomotor skills, we tested the hypothesis that the most vulnerable phases are the early and late ones, thus expecting a quadratic relationship. For that, we paired 105 tadpoles with potential predators considering the developmental stages and morphometric measures of the tadpoles, as well as response variables related to latency and number of predator attacks. The vulnerability to predation is lower in advanced stages, during which the sensory and cognitive advantages should play a predominant role. Interestingly, a quadratic relationship trend was also observed, indicating that late larval stages also suffer from locomotor disadvantages. None of predictor variables affected latency, suggesting that the decision to attack and the insistence on capture depend largely on the predator. All morphological variables were highly correlated, indicating that they can be equivalent. However, total tadpole length and length of the tail better describe attack vulnerability.