Doctor of Philosophy
Date of Defense
Robert E. Ricklefs, Ph.D.
Oxidative stress has been implicated in mediating trade-offs in the evolution of life histories. Oxidative stress results from an imbalance in the production of free radicals and an organism’s antioxidant defenses. Higher metabolic rates associated with more rapid growth and shorter development periods may increase oxidative stress and accumulated cellular damage in embryonic tissues. In my dissertation I explored oxidative stress and antioxidant defenses in avian embryos. I measured levels of oxidative stress in tissues of different stage embryos of Japanese quail (Coturnix japonica), and tested if patterns of lipid peroxidation could be explained by changes in the developing embryo’s metabolic rate. The amount of lipid peroxidation at any stage was positively related to the cumulative amount of oxygen consumed by the developing embryo. To explore differences in oxidative stress during embryonic development and its relationship to incubation length, I collected samples of embryonic tissue from five avian species with different embryo development periods. Samples were collected from: chicken (Gallus gallus domesticus), Japanese quail, American herring gull (Larus smithsonianus), mallard duck (Anas platyrhynchos), and Leach’s storm-petrel (Oceonodroma leucorhoa). Incubation in these species ranges from 17 days (quail) to 42 days (storm-petrel). To quantify variation in oxidative stress between species, I measured levels of oxidation to DNA and lipids. I also quantified variation in antioxidant defenses and DNA repair capability. Overall, embryos from species with shorter incubation periods had higher levels of oxidative stress than embryos from more slowly developing species. There were no differences in antioxidant defense or repair of oxidized nucleotides between species. These results suggest that there may be a trade-off between incubation length and oxidative stress during development.
Tsunekage, Toshi, "Oxidative Stress in Avian Embyros" (2015). Dissertations. 142.