Immediate and delayed effects of growth conditions on ageing parameters in nestling zebra finches

International audienceConditions experienced during development and growth are of crucial importance as they can have significant influence on the optimisation of life histories. Indeed, the ability of an organism to grow fast and achieve a large body size often confers short and long term fitness benefits. However, there is good evidence that organisms do not grow at their maximal rates as growth rates seem to have potential costs on subsequent lifespan. Several proximate causes of such a reduced lifespan might be involved. Among them, one emerging hypothesis is that growth impacts adult survival and/or longevity through a shared, endpoint, ageing mechanism: telomere erosion. In this study, we manipulated brood size in order to investigate if rapid growth (chicks in reduced broods) is effectively done at the cost of a short (end of growth) and long term (at adulthood) increase of oxidative damage and telomere loss. Contrary to what we expected, chicks from the enlarged broods displayed more oxidative damage and had shorter telomeres at the end of the growth period and at adulthood. Our study extends the understanding of the proximate mechanisms involved in the trade-off between growth and ageing. It highlights that adverse environmental conditions during growth can come at a cost via transient increased oxidative stress and pervasive eroded telomeres. Indeed, it suggests that telomeres are not only controlled by intrinsic growth rates per se but may also be under the control of some extrinsic environmental factors that may get our understanding of the growth ageing interaction more complicated