Age estimation in a long-lived seabird (Ardenna tenuirostris) using DNA methylation-based biomarkers

Age structure is a fundamental aspect of animal population biology. Age is strongly related to individual physiological condition, reproductive potential and mortality rate. Currently, there are no robust molecular methods for age estimation in birds. Instead, individuals must be ringed as chicks to establish known-age populations, which is a labour intensive and expensive process. The estimation of chronological age using DNA methylation is emerging as a robust approach in mammals including humans, mice and some non-model species. Here we quantified DNA methylation in whole blood samples from a total of 71 known-age Short-tailed shearwaters (Ardenna tenuirostris) using digital restriction enzyme analysis of methylation (DREAM). The DREAM method measures DNA methylation levels at thousands of CpG dinucleotides throughout the genome. We identified seven CpG sites with DNA methylation levels that correlated with age. A model based on these relationships estimated age with a mean differenc...