Oxidative stress and behavioral responses of moorish geckos (Tarentola mauritanica) submitted to the presence of an introduced potential predator (Hemorrhois hippocrepis)

Stressful situations induce an increase in the production of reactive oxygen species (ROS) which can lead to molecular damage and alteration of cell function. The introduction of new potential predators induces physiological stress in native fauna. However, behavioral responses have been reported in preys, demonstrating an induction of the defenses against alien species. Behavioral and antioxidant enzyme responses in the moorish gecko, Tarentola mauritanica, against the invasive predator horseshoe whip snake (Hemorrhois hippocrepis) were assessed. Behavior was recorded and a tissue sample from the tail was collected after placing the gecko in a terrarium with previous absence or presence of the snake in ‘Control’ and ‘H. hippocrepis’ groups, respectively. Fifteen behavioral variables were examined, including tongue flick (TF) and locomotion patterns. Antioxidant enzyme activities -catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR)-, and the levels of reduced (GSH) and oxidized glutathione (GSSG), glutathione/glutathione disulfide ratio (GSH/GSSG) and malondialdehyde (MDA) concentrations were measured in the tissue sampled. Geckos exposed to the snake's odor showed a higher number of TF, longer amounts of time remaining motionless or moving in slow motion and they spent less time on the ground in comparison to the ‘Control’ group. The presence of the snake produced a significant increase in the activities of CAT, SOD and GR and a decrease in the GSH/GSSG ratio in T. mauritanica individuals exposed to the snake's scent. Thus, both behavioral responses and oxidative stress biomarkers clearly showed that T. mauritanica is able to recognize H. hippocrepis as a potential predator, despite being a recently introduced snake at the Balearic Islands.