Telomere Length Decreases with Age and Reflects Early-Life Environment but Not Adult Condition in a Long-Lived Migratory Bird.

AbstractWithin species and populations, individuals often differ in their coping styles and more generally in their life history strategies. This heterogeneity in individual life history is classically reflected by variation in physiological performance, survival probabilities, and reproductive success. In many vertebrate species, physiological performance is partially mediated by glucocorticoids and declines with age through senescence, which may be reflected by variation in telomere length. Telomeres are noncoding DNA sequences that typically shorten with age. Their dynamics have been related to oxidative stress and energy allocated to DNA repair mechanisms. In this study, the link between telomere length and several proxies of individual quality was investigated in female greater snow geese, a long-lived migratory species. More specifically, we examined the relationships between telomere length, stress-induced corticosterone (the main avian glucocorticoid), body size, and postbreeding body condition. In goslings, telomere length was highly variable and explained by year of birth. In adult females, our results showed the expected decline of telomere length with age. Telomere length adjusted for age increased with body size but did not vary with body condition or stress-induced corticosterone levels. Conversely, we show that female postbreeding body condition varies with age, increasing until they are 8 yr old and decreasing at a later age. Because body size is primarily determined during development, our results point to telomeres being a good indicator of the conditions experienced during early life. In contrast, it does not seem to be related to the amount of endogenous reserve during adult life. This supports the idea that telomere length could be a reliable marker of early developmental conditions and potentially of individual quality.