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

University Of California-Davis, Davis CA

Investigators

Abstract

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.