The relationship of telomere length to baseline corticosterone levels in nestlings of an altricial passerine bird in natural populations.

Verónica Quirici,Rodrigo A Vásquez,Claudia Jimena Guerrero,Jesse S Krause,John C Wingfield

doi:10.1186/s12983-016-0133-5

Abstract

BackgroundEnvironmental stressors increase the secretion of glucocorticoids that in turn can shorten telomeres via oxidative damage. Modification of telomere length, as a result of adversity faced early in life, can modify an individual’s phenotype. Studies in captivity have suggested a relationship between glucocorticoids and telomere length in developing individuals, however less is known about that relationship in natural populations.MethodsIn order to evaluate the effect of early environmental stressors on telomere length in natural populations, we compared baseline corticosterone (CORT) levels and telomere length in nestlings of the same age. We collected blood samples for hormone assay and telomere determination from two geographically distinct populations of the Thorn-tailed Rayadito (Aphrastura spinicauda) that differed in brood size; nestlings body mass and primary productivity. Within each population we used path analysis to evaluate the relationship between brood size, body mass, baseline CORT and telomere length.ResultsWithin each distinct population, path coefficients showed a positive relationship between brood size and baseline CORT and a strong and negative correlation between baseline CORT and telomere length. In general, nestlings that presented higher baseline CORT levels tended to present shorter telomeres. When comparing populations it was the low latitude population that presented higher levels of baseline CORT and shorter telomere length.ConclusionsTaken together our results reveal the importance of the condition experienced early in life in affecting telomere length, and the relevance of integrative studies carried out in natural conditions.

Highlights

Environmental stressors increase the secretion of glucocorticoids that in turn can shorten telomeres via oxidative damage
We tested the hypothesis that brood size affects baseline CORT and how this affects telomere length
In the low latitude population, brood size had a negative effect on body mass and body mass had a negative effect on baseline CORT (Fig. 2)

Summary

Introduction

Environmental stressors increase the secretion of glucocorticoids that in turn can shorten telomeres via oxidative damage. In nestlings of altricial bird species, where the newly hatched young lack down and mobility, are not able to obtain food on their own, and must be cared for by adults, environmental stressors are buffered by parents. Even where parental quality is high, Such perturbations activate the hypothalamic-pituitaryadrenal (HPA) axis, resulting in increased levels of the steroid hormone corticosterone (CORT), the primary glucocorticoid in birds [10, 11]. The first is an approximation of the seasonal baseline level that the animal should maintain to be able to cope with the predictable demands of the current life-history stage [13, 14], so it reflects long-term adaptation.

Objectives

Methods

Results

Discussion

Conclusion