High heritability of telomere length and low heritability of telomere shortening in wild birds

Telomere length and telomere shortening predict survival in many organisms. This raises the question of the contribution of genetic and environmental effects to variation in these traits, which is still poorly known, particularly for telomere shortening. We used experimental (cross-fostering) and statistical (quantitative genetic ‘animal’ models) means to disentangle and estimate genetic and environmental contributions to telomere length variation in pedigreed free-living jackdaws (Corvus monedula). Telomere length was measured twice in nestlings, at ages 4 (n=715) and 29 days (n=474), using TRF-analysis, adapted to exclude interstitial telomeric sequences. Telomere length shortened significantly over the nestling period (10.4±0.3 bp/day) and was highly phenotypically (rP=0.95±0.01) and genetically (rG>0.99±0.01) correlated within individuals. Additive genetic effects explained a major part of telomere length variation among individuals, with its heritability estimated at h2=0.74 on ...