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

本研究旨在确定构成衰老过程的机制，并在自由生活的脊椎动物自然种群中证明其适应性后果。值得注意的是，鸟类的寿命比同等大小的哺乳动物更长。树燕之所以被用作模型系统，是因为大量已知年龄的个体可以每年重复捕获和采样，而且它们的繁殖成功率很容易在它们的一生中进行测量。本研究考察了与自由生活鸟类衰老相关的生理因素的自然变异。来自单个树燕的纵向样本将用于追踪氧化应激、端粒失调（保护编码DNA的染色体帽，但随着细胞分裂而缩短）和免疫功能下降。生理机制的个体差异在多大程度上解释了观察到的生存和繁殖成功的差异，这将使研究人员能够确定这些可能发生衰老的替代途径的相对重要性。不同年龄鸟类的横截面样本将确定每种生理性状的种群平均值如何随年龄变化，纵向和横截面样本的比较将区分个体衰老的影响和不同性状值个体之间的选择影响。这项研究将包括一项旨在提高个体燕子代谢率的实验，以验证氧化代谢和随之而来的自由基的产生对衰老和端粒缩短的进展具有因果关系的假设。它将为高中生、本科生和研究生以及高中科学教师提供实验室和实地培训。这项研究将使对衰老感兴趣的研究人员能够将表型特征值与死亡风险联系起来，并确定衰老的进化重要机制。此外，本研究将为大大加强生活史策略的权衡研究提供新的工具。

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.