Collaborative Research: Oxidative Stress, Telomere Dynamics and Aging in a Free-living Organism

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This research is designed to identify the mechanisms that comprise the process of aging and to demonstrate its fitness consequences within a natural population of free-living vertebrates. Birds are noteworthy for having longer life spans than similar sized mammals. Tree swallows are the model system used because a large number of known-aged individuals can be repeatedly captured and sampled from year to year, and their reproductive success is easily measured across their life span. This research examines natural variation in physiological factors associated with aging in free-living birds. Longitudinal samples from individual tree swallows will be used to track oxidative stress, dysregulation of telomeres (chromosomal caps that protect coding DNA but shorten with cell division), and immune function decline. The extent to which individual variation in physiological mechanisms accounts for observed differences in survival and reproductive success will allow the researchers to identify the relative importance of these alternative pathways through which aging may occur. Samples from a cross-section of birds of different ages will identify how population averages for each physiological trait change with age, and comparison of the longitudinal and cross sectional samples will separate effects of individual aging from effects of selection between individuals with different trait values. The research will include an experiment designed to increase metabolic rates of individual swallows to test the hypothesis that oxidative metabolism and the attendant production of free radicals is causally important to the progression of aging and telomere shortening. It will provide laboratory and field training of high school, undergraduate, and graduate students as well as involvement by high school science teachers. This research will enable researchers interested in aging to link phenotypic trait values and risks of mortality, and identify evolutionarily important mechanisms of aging. In addition, this research will provide new tools to substantially strengthen the study of trade-offs in life history strategies.