Abstract:
The risk of predation and the costs and benefits of diverse anti-predator strategies can shift across the life stages of an
organism. Yet, empirical examples of ontogenetic switches in defense mechanisms are scarce. Anurans represent an alleged
exception; previous meta-analytic work suggests that unpalatability of developing anurans is “rare”, whereas adult anurans
in many lineages are well defended by toxic and/or unpalatable skin secretions. Here, we revisit the question of the unpalat-
ability of anuran young in a meta-analysis of the relative proportion of prey consumed within 922 predation tests, including
135 anuran species. We tested the hypotheses that a predator’s propensity to consume anuran young depends on (1) prey
family, (2) predator manipulation strategy, and (3) prey ontogenetic stage. We used a binomial mixed model approach with
considerations for multiple effect sizes within studies to evaluate the log odds ratio of the proportion of prey consumed by
individual predators. Prey consumption was highly variable, but toads (Bufonidae) were consumed in lower proportions.
Chewing invertebrates consumed more anuran prey than biting vertebrates. Late stage tadpoles were more vulnerable to
predation than other stages of anuran ontogeny. However, more studies are needed to unravel the roles of development and
evolutionary history in the chemical ecology of anuran young. This synthesis provides clear meta-analytic evidence that
relative unpalatability is an important component in the anti-predator defenses of young in some anuran families, calling into
question the degree to which chemically defended anuran families undergo ontogenetic switches in anti-predator strategies.
