Invasive predator snake induces oxidative stress responses in insular amphibian species.

The presence of predators induces physiological stress responses in preys to avoid being captured. A stressful situation enhances reactive oxygen species production with potential damage to macromolecules and alterations in oxidant defences levels. The antioxidant enzyme response of the endemic Majorcan Midwife toad (Alytes muletensis) and the Balearic green toad (Bufotes balearicus) tadpoles against an invasive predator, the viperine snake (Natrix maura) was investigated. Tadpoles were introduced in aquaria containing N. maura exudates during 24h. Antioxidant enzyme activities - catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), superoxide dismutase (SOD) - and reduced glutathione (GSH) and malondialdehyde (MDA) concentrations were measured in tadpoles. The presence of snake exudates induced a significant increase in CAT and GR activities and in GSH levels (p<0.05) in A. muletensis tadpoles, whereas no significant differences were reported in any of the parameters analysed in B. balearicus tadpoles. In conclusion, the presence of N. maura exudates is capable to induce an antipredatory response in the endemic A. muletensis tadpoles but not in B. balearicus.