Effect of developmental hypoxia on mitochondrial O2 consumption. Mitochondrial O2 consumption was measured in juvenile snapping turtles from normoxic (N21, red circles, n = 8) and hypoxic (H10, blue squares, n = 8) incubations. Each panel represents a respiratory state. (A) Leak respiration with substrates for complex I, in the absence of adenylates (LeakN,CI). (B) Leak respiration with substrates for complex I, in the presence of adenylates (LeakT,CI). (C) Leak respiration with substrates for complexes I and II, in the presence of adenylates (LeakT,CI+CII). (D) Oxidative phosphorylation, with substrates for complex I (OXPHOSCI). (E) Oxidative phosphorylation with substrates for complexes I and II (OXPHOSCI+CII). (F) Electron-transfer capacity, with substrates for complexes I and II (ETCI+CII). (G) Electron-transfer capacity, with substrates for complex II (ETCII). (H) Electron donation to complex IV (CIV). Statistical significance was assessed with individual generalized linear models, followed by Sidak post hoc tests, to assess the effect of developmental O2 (N21 vs. H10). Values were considered significant when P ≤ 0.05, which are denoted by asterisks (*).