A1 Refereed original research article in a scientific journal
Epigenetic age estimation of wild mice using faecal samples
Authors: Hanski, Eveliina; Joseph, Susan; Raulo, Aura; Wanelik, Klara M.; O'Toole, Áine; Knowles, Sarah C. L.; Little, Tom J.
Publisher: Wiley-Blackwell
Publication year: 2024
Journal: Molecular Ecology
Journal name in source: Molecular ecology
Journal acronym: Mol Ecol
Article number: e17330
Volume: 33
Issue: 8
ISSN: 0962-1083
eISSN: 1365-294X
DOI: https://doi.org/10.1111/mec.17330
Web address : https://onlinelibrary.wiley.com/doi/10.1111/mec.17330
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/387614680
Age is a key parameter in population ecology, with a myriad of biological processes changing with age as organisms develop in early life then later senesce. As age is often hard to accurately measure with non-lethal methods, epigenetic methods of age estimation (epigenetic clocks) have become a popular tool in animal ecology and are often developed or calibrated using captive animals of known age. However, studies typically rely on invasive blood or tissue samples, which limit their application in more sensitive or elusive species. Moreover, few studies have directly assessed how methylation patterns and epigenetic age estimates compare across environmental contexts (e.g. captive or laboratory-based vs. wild animals). Here, we built a targeted epigenetic clock from laboratory house mice (strain C57BL/6, Mus musculus) using DNA from non-invasive faecal samples, and then used it to estimate age in a population of wild mice (Mus musculus domesticus) of unknown age. This laboratory mouse-derived epigenetic clock accurately predicted adult wild mice to be older than juveniles and showed that wild mice typically increased in epigenetic age over time, but with wide variation in epigenetic ageing rate among individuals. Our results also suggested that, for a given body mass, wild mice had higher methylation across targeted CpG sites than laboratory mice (and consistently higher epigenetic age estimates as a result), even among the smallest, juvenile mice. This suggests wild and laboratory mice may display different CpG methylation levels from very early in life and indicates caution is needed when developing epigenetic clocks on laboratory animals and applying them in the wild.
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Funding information in the publication:
This work was funded by The Osk. Huttunen Foundation studentship and the National Geographic Society (Early Career grant reference No. EC-58520R-19) to EH, the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement no. 851550) and a NERC fellowship (NE/L011867/1) to SCLK and the British Ecological Society (BES) to TJL and SCLK.
