Data from: Telomere length reflects reproductive effort indicated by corticosterone levels in a long-lived seabird

Telomere length is a candidate biomarker of ageing and phenotypic quality, but little is known of the (physiological) causes of telomere length variation. We previously showed that individual common terns Sterna hirundo with high reproductive success had short telomeres independent of age, and this pattern was particularly strong in the longer telomeres of the within-individual telomere length distribution. To test whether this relation can be attributed to effects of reproductive effort, we investigated baseline corticosterone in relation to reproductive success (number of fledglings) and telomere length. In this context we assume that variation in baseline corticosterone can be interpreted as index of energy expenditure and allostatic load. Males with higher corticosterone levels during incubation, compared between and within individuals, achieved higher reproductive success and had shorter telomeres. The effect on telomeres was more pronounced in corticosterone measured later in incubation, and in the longer telomeres of the within-individual telomere length distribution. Female corticosterone level during incubation was neither related to reproductive success nor to telomere length. That we observed these effects only in males mirrors different parental roles during reproduction in the common tern, where males do most of the chick provisioning. The negative association between reproductive success and telomere length suggests individual differences in reproductive effort as reflected in, or mediated by, baseline corticosterone. We see this result as a promising step towards unravelling the physiological causes of variation in telomere length and the costs of reproduction.端粒长度是衰老与表型质量的候选生物标志物，但目前对端粒长度变异的生理成因仍知之甚少。此前我们的研究表明，繁殖成功率较高的个体普通燕鸥（Sterna hirundo）端粒长度较短，且该规律不受年龄影响；在个体内端粒长度分布的长端粒区段中，这一特征尤为显著。为验证上述关联是否可归因于繁殖投入的影响，我们围绕基础皮质酮（corticosterone）水平与繁殖成功率（出飞雏鸟数量）及端粒长度之间的关联展开了研究。本研究假设，基础皮质酮水平的变异可作为能量消耗与稳态负荷的指标。个体间与个体内对比显示，孵卵期皮质酮水平较高的雄性燕鸥，其繁殖成功率更高且端粒更短。且孵育后期测得的皮质酮水平对端粒的影响更为显著，同样在个体内端粒长度分布的长端粒区段中该效应更为突出。雌性燕鸥孵卵期的皮质酮水平则与繁殖成功率及端粒长度均无关联。上述效应仅在雄性个体中显现，这一现象反映了普通燕鸥繁殖期间双亲的亲本分工——雄性承担绝大多数雏鸟的育雏任务。繁殖成功率与端粒长度之间的负相关关系表明，繁殖投入的个体差异可通过基础皮质酮水平体现或介导。我们认为，该研究结果为阐明端粒长度变异的生理成因及繁殖成本的解析迈出了富有前景的一步。