Ontogenetic modulation of risk perception and decision making in larval anurans

To select cost-effective defensive responses, prey need to fine-tune defensive responses by integrating reliable information about predation risk with their own physiological state and energetic needs. While it is difficult to assess the actual perceived level of risk, we hypothesized that stage-related variation in defensive responses to different predation cue concentrations may offer valuable insight into decision making under predation risk. To test this hypothesis, we examined Italian agile frog (Rana latastei) tadpoles’ sensitivity to both fed and fasted predator cues at varying concentrations (1:1, 1:10, 1:100, 1:500) and two developmental stages (26-28 and 30-31 Gosner stages). Younger tadpoles responded similarly to both types of cues, by markedly lowering activity levels when exposed at 1:1 and 1:10 cues, while no significant difference from the control was recorded at low cue concentrations. Older tadpoles in contrast, showed heightened sensitivity to fed predator cues, responding even at 1:100, while largely ignoring cues from fasted predators. These results highlight a developmental shift in risk assessment, consistent with changing trade-offs between predator avoidance and other life-history priorities. This shift suggests that ontogenetic changes shape not only the strength but also the selectivity of perceived risk, reflecting more nuanced decision-making as developmental priorities evolve.