Dissertation Research: Linking lifetime processes with telomere dynamics: signals, reproductive effort, and senescence in a warbler

鸟类精心制作的歌声和羽毛装饰通常被认为是雄性品质的标志；因此，对显示做出反应的雌性应该通过增加后代的数量或质量来获得生殖利益。然而，为了让雌性继续做出回应，信号必须是诚实的，这表明某种机制可以防止雄性欺骗。对于那些繁殖多年的物种来说，两个导致衰老的过程可能会通过在性展示和长寿之间进行权衡来确保信号的诚实。其中一个过程涉及端粒，它是重复的DNA序列，作为每条染色体末端的保护帽，随着年龄的增长而缩短；第二个过程是氧化应激，当细胞代谢的副产物破坏DNA和其他细胞成分时发生。研究人员将测量在纽约州北部繁殖的普通黄喉莺野生种群的性信号、繁殖成功率、端粒缩短和氧化应激。他们将从两方面探讨生殖投资和老龄化之间的权衡。首先，他们将在我们的长期数据集中寻找性信号、终生生殖成功、端粒缩短和氧化损伤之间的关系。其次，他们将使用激素植入来实验性地增加生殖投资，并测量由此产生的对端粒损失和氧化损伤的影响。在性信号上投入过多的个体将会通过快速的生理衰老和缩短寿命来付出高昂的代价。了解复杂的性状组合相互作用决定终生生殖成功的方式，对于预测形成重要生活史性状的进化结果至关重要，例如物种内和物种间的衰老模式和生殖策略。

The elaborate songs and plumage ornaments of birds are generally thought to advertise male quality; therefore, females that respond to displays should gain a reproductive benefit through increased quantity or quality of offspring. However, in order for females to continue responding, signals must be honest, suggesting that some mechanism prevents males from cheating. For species that breed over multiple years, two processes that contribute to aging may ensure signal honesty by enforcing a trade-off between investment in sexual displays and investment in longevity. One process involves telomeres, which are repeated DNA sequences that serve as protective caps on the ends of each chromosome and shorten with age; the second process, oxidative stress, occurs when the by-products of cellular metabolism damage DNA and other cell constituents. The investigators will measure sexual signals, reproductive success, telomere shortening, and oxidative stress in a wild population of common yellowthroat warblers breeding in upstate New York. They will explore trade-offs between reproductive investment and aging in two ways. First, they will look for relationships between sexual signals, lifetime reproductive success, telomere shortening, and oxidative damage in our long-term data set. Second, they will use hormone implants to experimentally increase reproductive investment and measure the resulting impact on telomere loss and oxidative damage. Individuals that invest heavily in sexual signals are expected to pay a high cost through fast physiological aging and reduced longevity. Understanding the way that complex suites of traits interact to determine lifetime reproductive success is essential in predicting evolutionary outcomes that shape important life history traits, such as aging patterns and reproductive strategies, both within and across species.