Differential Success of Prey Escaping Predators: Tadpole Vulnerability or Predator Selection?

Species Inhabiting habitats with different predators are expected to show divergent phenotypes for antipreciator traits. Here, we used a predator-prey system of dragonfly larvae and tadpoles to determine If vulnerability to a common predator differs in species with contrasting antipredator strategies. We examined the vulnerability of tadpoles of Rana temporaria and Bufo bufo to predation by Aeshna larvae when the two species co-occur In the same arena. Our results demonstrated that tadpoles of Bufo were more vulnerable than tadpoles of Rana despite the observation that dragonfly larvae did not show Initial preferences for either prey species. Differences In susceptibility to predation seem to be associated with their low performance In evasive responses. Most Important, our data suggest that despite chemical protection that effectively prevented the consumption of B. bufo by Aeshna larvae, Injured tadpoles that otherwise had survived are at a high risk of being cannibalized. This loss of survival advantage of a chemical defense is an indirect result of two antipredator responses: the effectiveness of the chemical defense Itself and the immobility of refused tadpoles.