Search for: All records

Stress can influence lifespan in both positive and negative ways, depending on exposure intensity and duration. However, mechanisms driving positive stress effects on lifespan remain poorly understood. Prolonged hypoxia extends the lifespan of overwintering prepupal Megachile rotundata. Here, we explored telomere length and reduced oxidative stress as potential mechanisms of this extended lifespan. We hypothesized high antioxidant capacity under hypoxia reduces oxidative damage and telomere loss. We exposed prepupae to 10%, 21% or 24% oxygen for up to 9 months and measured monthly survival, telomere length, antioxidant capacity and lipid peroxidation across treatment duration for prepupae and adults. After 9 months of exposure, survival was highest in hypoxia and lowest in hyperoxia. Telomere length did not differ among oxygen treatments but increased in adults compared with prepupae. Total antioxidant capacity and lipid peroxidation showed no significant differences among oxygen treatments, suggesting compensatory responses to maintain baseline oxidative levels. 

The mechanisms that contribute to variation in lifetime reproductive success are not well understood. One possibility is that telomeres, conserved DNA sequences at chromosome ends that often shorten with age and stress exposures, may reflect differences in vital processes or influence fitness. Telomere length often predicts longevity, but longevity is only one component of fitness and little is known about how lifetime reproductive success is related to telomere dynamics in wild populations. We examined the relationships between telomere length beginning in early life, telomere loss into adulthood and lifetime reproductive success in free-living house sparrows ( Passer domesticus ). We found that females, but not males, with longer telomeres during early life had higher lifetime reproductive success, owing to associations with longevity and not reproduction per year or attempt. Telomeres decreased with age in both sexes, but telomere loss was not associated with lifetime reproductive success. In this species, telomeres may reflect differences in quality or condition rather than the pace of life, but only in females. Sexually discordant selection on telomeres is expected to influence the stability and maintenance of within population variation in telomere dynamics and suggests that any role telomeres play in mediating life-history trade-offs may be sex specific.