Data from: How do growth and sibling competition affect telomere dynamics in the first month of life of long-lived seabird?

Telomeres are nucleotide sequences located at the ends of chromosomes that promote genome stability. Changes in telomere length (dynamics) are related to fitness or life expectancy, and telomere dynamics during the development phase are likely to be affected by growth and stress factors. Here, we examined telomere dynamics of black-tailed gull chicks (Larus crassirostris) in nests with and without siblings. We found that the initial telomere lengths of singletons at hatching were longer than those of siblings, indicating that singletons are higher-quality chicks than siblings in terms of telomere length. Other factors likely affecting individual quality (i.e., sex, laying date, laying order of eggs, and clutch size) were not related to telomere lengths. Within broods, initial telomere lengths were longer in older chicks than in younger chicks, suggesting that maternal effects, which vary with laying sequence, influence the initial lengths. Additionally, telomeres of chicks with a sibling showed more attrition between hatching and fledging than those of singleton chicks, suggesting that being raised with siblings can cause a sustained competitive environment that leads to telomere loss. High growth rates were associated with a low degree of telomere shortening observed in older siblings, perhaps because slower growth reflects higher food stress and/or higher aerobic metabolism from increased begging effort. Our results show that developmental telomere attrition was an inevitable consequence in two-chick nests in the pre- and post-hatching microenvironments due to the combination of social stress within the nest and maternal effects. The results of our study shed light on telomere dynamics in early life, which may represent an important physiological undercurrent of life-history traits.端粒（telomeres）是位于染色体末端的核苷酸序列，可维护基因组稳定性。端粒长度的动态变化与个体适合度及寿命息息相关，发育阶段的端粒动态变化易受生长与应激因素的影响。本研究以黑尾鸥（Larus crassirostris）雏鸟为研究对象，考察了存在同窝雏鸟与不存在同窝雏鸟的巢穴中雏鸟的端粒动态变化。研究发现，孵化初期单雏鸟的初始端粒长度长于同窝雏鸟，表明从端粒长度维度来看，单雏鸟的个体质量更高。其他可能影响个体质量的因素（即性别、产卵日期、卵的产卵顺序以及窝卵数）均与端粒长度无显著关联。在同窝雏鸟内部，孵化初期年长雏鸟的初始端粒长度长于年幼雏鸟，这提示随产卵序列变化的母体效应会对初始端粒长度产生影响。此外，有同窝雏鸟的雏鸟，其端粒在孵化至出飞阶段的磨损程度显著高于单雏鸟，这表明与同窝雏鸟共同抚育会形成持续性的竞争环境，进而导致端粒丢失。高生长速率与年长雏鸟的端粒缩短程度较低显著相关，这或许是因为较慢的生长速率反映了更高的食物应激，或是乞食行为增加所导致的有氧代谢水平升高。本研究结果表明，在双雏巢穴的孵化前后微环境中，由于巢穴内的社会应激与母体效应共同作用，发育性端粒磨损是一种必然结果。本研究阐明了早期生命阶段的端粒动态变化，这或许是生活史特征背后一项重要的生理基础。