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.