Stress exposure in early post-natal life reduces telomere length: an experimental demonstration in a long-lived seabird

Abstract

Exposure to stressors early in life is associated with faster ageing and reduced longevity. One important mechanism that could underlie these late life effects is increased telomere loss. Telomere length in early post-natal life is an important predictor of subsequent lifespan, but the factors underpinning its variability are poorly understood. Recent human studies have linked stress exposure to increased telomere loss. These studies have of necessity been non-experimental and are consequently subjected to several confounding factors; also, being based on leucocyte populations, where cell composition is variable and some telomere restoration can occur, the extent to which these effects extend beyond the immune system has been questioned. In this study, we experimentally manipulated stress exposure early in post-natal life in nestling European shags (Phalacrocorax aristotelis) in the wild and examined the effect on telomere length in erythrocytes. Our results show that greater stress exposure during early post-natal life increases telomere loss at this life-history stage, and that such an effect is not confined to immune cells. The delayed effects of increased telomere attrition in early life could therefore give rise to a ‘time bomb’ that reduces longevity in the absence of any obvious phenotypic consequences early in life.

Bill size correlates with telomere length in male American Redstarts

“…This confirms that specific components of body size and TL are correlated in young birds (Caprioli et al 2013), and supports the idea that the determinants of some components of body size are also important determinants of TL. This correlation probably results from developmental conditions that affect simultaneously growth and developmental telomere dynamics (Boonekamp et al 2014;Herborn et al 2014), but it might also result from genetic factors that might concomitantly govern bill size and telomere length.…”

“…In addition, laying order is also known to affect yolk oxidative status, and, potentially, the telomere length of developing nestling (Rubolini et al 2006). This emphasizes that developmental conditions, such as sibling competition, may simultaneously account for inter-individual variations in TL and morphology (bill morphology: Sockman 2012; telomeres: Boonekamp et al 2014;Herborn et al 2014). …”

“…hatch-year birds, HY, and from 2 to 7 years old, i.e., after hatch-year birds, AHY). Because poor developmental conditions are known to increase the rate of telomere shortening (Boonekamp et al 2014;Herborn et al 2014) and may simultaneously limit growth during the pre-adult period, we predicted that body size should be positively correlated with TL in HY Redstarts (prediction 1). As explained earlier, body size should be disconnected from telomere dynamics during adulthood, and, therefore, we also predicted that the correlation between body size and TL should attenuate in AHY Redstarts (prediction 2).…”

“…However, adult TL is not only determined by events occurring during adult life but also by the initial TL at the time when individuals enter the adult life stage. TL is at least partly heritable (Olsson et al 2011;Horn et al 2011;Reichert et al 2014) and most of the telomere shortening occurs during development (Foote et al 2011;Pauliny et al 2012;Caprioli et al 2013), suggesting that variation in conditions during the period leading up to adulthood determines variation in telomere length in wild birds (Geiger et al 2012;Boonekamp et al 2014;Herborn et al 2014). Interestingly, poor developmental conditions are associated with impaired growth and, under some circumstances, with reduced adult size (Merïla 1997).…”

A migratory lifestyle is associated with shorter telomeres in a songbird (Junco hyemalis)

“…Indeed, recent ornithological studies have linked telomere lengths and their relative shortening rates with lifespan Mauck 2008, Heidinger et al 2012). Increased telomere attrition rates have also been linked with energetically expensive time periods or circumstances, such as breeding (Bauch et al 2013, Sudyka et al 2014, stress during post-natal development (Herborn et al 2014), and decreased time at wintering grounds (Schultner et al 2014). Thus, telomere attrition might reflect the physiological costs involved in shaping whether animals engage in migration, but it has yet to be tested whether telomere loss differs between migrants and residents.…”