Assessing the effect of acute exposure to predator risk in amphibians at different temperatures. An oxidative stress approach in tadpoles

Abstract

We investigated physiological stress in response to predation risk in tadpoles of two Pleurodemaspecies that differ in phenotypic responses but, according to previous work, behave similarly whenthreatened by predation (freezing). To assess whether physiological responses vary with risk and temperature, we measured oxidative stress markers at three levels of non-consumptive predation risk (predator cues, alarm cues and control) and at two temperatures (15 °C?25 °C). The risk treatments caused no significant differences in antioxidant enzyme activity (catalase, glutathione-S-transferase, superoxide dismutase) and lipid peroxidation (LPO) levels. Levels of oxidative stress markers (CAT and LPO) varied with temperature, with higher mean values in tadpoles exposed to high temperature. Overall, oxidative stress differed between species, with higher levels of enzyme activities and lower LPO levels in P. bufoninum than P. thaul. We conclude that the risks testedunder the conditions of this experiment did not cause changes in the markers tested. These results provide new insight into phenotypic changes in Pleurodema tadpoles exposed to predation risk, introducing data on the physiological cost. The performance of antioxidant systems in this predator?prey system reveals the need for further knowledge of the effect of stressors on ectotherm interactions, and relevance in their life history.