Figure 6

Indicators of oxidative stress. (a) First two PCA axes of oxidative stress enzyme concentrations. Arrows show loadings of the four enzymes: superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR) and glutathione peroxidase (GPx). Also shown are boxplots of (b) malondialdehyde concentration (nmol MDA/ml) and (c) of ratio of reduced glutatione (GSH) to oxidazed glutathione (GSSG). Black versus grey symbols and illustrations refer to dark versus light tadpoles, where n = 5 per group.