Meeting Abstract
Earlier breeders in the temperate-zone often have higher reproductive success than those that breed later in the season, yet few individuals breed early. Early breeding female annual survival has not been found to differ from late-breeding females; however, there may be other long-term costs. We hypothesized that one potential cost for early breeding females is that they may experience accelerated aging. Telomere dynamics are increasingly used as a biomarker for studying biological aging. Telomeres, the repetitive DNA sequences on the ends of chromosomes, serve as a proxy for biological aging because they shorten with age and in response to oxidative stress. Breeding early may increase exposure to stressors, such as cooler temperatures and extreme weather events. We utilized historical nesting records and blood samples of 106 female Dark-eyed Juncos (Junco hyemalis) between 1990 and 2016 to test whether breeding early in the season is associated with greater rate of aging as reflected in higher telomere loss. Our data show that earlier breeding females exhibited greater telomere loss over the following year compared with later breeding females. These findings indicate that biological aging may be a significant cost to early reproduction that may prevent the majority of individuals from breeding early, despite the apparent adaptive value of early breeding.
