Data from: Experimentally increased reproductive effort alters telomere length in the blue tit (Cyanistes caeruleus)

Telomeres have recently been suggested to play important role in ageing and are considered to be a reliable ageing biomarkers. The life history theory predicts that costs of reproduction should be expressed in terms of accelerated senescence, and some empirical studies do confirm such presumption. Thus, a link between reproductive effort and telomere dynamics should be anticipated. Recent studies have indeed demonstrated that reproduction may trigger telomere loss, but actual impact of reproductive effort has not received adequate attention in experimental studies. Here, we experimentally manipulated reproductive effort by increasing the brood size in the wild blue tit (Cyanistes caeruleus). We show that parents attending enlarged broods experienced larger yearly telomere decay in comparison to control birds attending unaltered broods. In addition, we demonstrate that the change in telomere length differs between sexes, but this effect was independent from our treatment. To our knowledge, this is the first experimental study in the wild revealing that telomere dynamics may be linked to reproductive effort. Thus, telomere shortening may constitute one of the potential proximate mechanisms mediating the costs of reproduction.

端粒（telomere）近来被认为在衰老过程中发挥关键作用，且被视作可靠的衰老生物标志物（biomarker）。生命史理论（life history theory）预测，繁殖成本会以衰老加速的形式体现，且已有多项实证研究证实了这一推测。因此，繁殖投入与端粒动态变化之间理应存在关联。近期研究确实表明，繁殖活动可能引发端粒损耗，但繁殖投入的实际影响在实验研究中尚未得到足够重视。本研究通过提升野生蓝山雀（Cyanistes caeruleus）的窝雏规模，对其繁殖投入进行了实验操控。结果显示，相较于抚育未调整窝雏数的对照组个体，抚育扩大后窝雏群的亲鸟每年的端粒衰减幅度显著更大。此外，本研究证实端粒长度的变化存在性别差异，但该效应与本次实验处理并无关联。据我们所知，本研究是首个在野生环境中开展的、揭示端粒动态变化或与繁殖投入相关的实验研究。由此可见，端粒缩短或许是介导繁殖成本的潜在近因机制之一。