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.