From nest to eternal rest: Molecular mechanisms underlying life-history variation in avian species

Following captive zebra finches and wild jackdaws from hatching until their natural death, this thesis aimed to elucidate how environmental, genetic, and epigenetic factors shape avian life history- the important stages of an organism’s life including growth, reproduction, aging and death.
One key finding is that growing up in larger broods can be stressful for young birds. Chicks in bigger broods had to beg the parents more for food, using up energy that could have otherwise been invested into growth, which later affected their health and lifespan. However, as adults, their ability to raise offspring was more influenced by how much food was available than by their early-life conditions. Birds raised in large broods also showed long-lasting differences in DNA methylation, a process that can turn genes on or off, which can contribute to their lower fitness.
This thesis also revealed that the rate at which zebra finch telomeres (protective caps on chromosomes) shorten is a strong predictor of lifespan, more so than measuring telomere length. Furthermore, this study uncovered intriguing patterns of DNA methylation on sex chromosomes (genetic structures which determine sex) of both species, suggesting a role in sex-specific aging rates and characteristics.
This thesis underscores the importance of expanding epigenetic research beyond mammalian models to gain a more comprehensive understanding of evolutionary processes across diverse taxa.