Oxidative stress refers to the imbalance between antioxidants and reactive oxygen species (ROS) generated during aerobic respiration, and it has often been hypothesized to play a central role in disease and life history evolution, including ageing. However, whether oxidative stress modulates patterns of growth, ageing or survival is still an enigma, largely because the high reactivity of ROS makes oxidative stress difficult to measure. This project aimed at resolving the long standing conundrum of the effects of oxidative stress on ageing and key fitness components using a novel non-invasive experimental approach that bypasses the side effects of pharmacological approaches. Captive zebra finches were exposed to hyperoxic air in a specially designed cabinet and this project was able to show that this manipulation increased oxidative stress levels in blood. The same hyperoxic treatment was then applied to nestlings to test how oxidative stress affects cellular ageing (telomere attrition). Telomeres are highly conserved DNA structures at the ends of eukaryotic chromosomes that shorten with cellular division and oxidative stress, thus suggesting a role in the ageing process. This part of the project is currently under analyses but upon publication, it will shed light on the roles of oxidative stress in life history evolution and telomere dynamics, and on whether the effects of oxidative stress on increased telomere shortening seen in vitro are also observed in vivo.
During this project, we were also able to test the effect of other extrinsic stressors on telomere shortening. Parasites are known to increase oxidative stress, and using a wild population of jackdaws this project showed that infection with a blood-sucking parasite during the developmental stage increases telomere shortening.
The results from this Action have significant societal impact. Understanding the underlying mechanisms of ageing in natural and captive model populations aids in the development of human ‘healthy ageing’ policies and conservation policies, for example by improving the management of endangered species that exhibit declining reproduction with age. By producing high impact publications the project will also inform the specialised audience ranging from evolutionary biologists, physiological ecologists or conservationists to immunologists or biomedical researchers.
