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Age estimation based on blood DNA methylation levels in brown bears
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  • Shiori Nakamura,
  • Jumpei Yamazaki,
  • Naoya Matsumoto,
  • Miho Inoue-Murayama,
  • Huiyuan Qi,
  • Masami Yamanaka,
  • Masanao Nakanishi,
  • Yojiro Yanagawa,
  • Mariko Sashika,
  • Toshio Tsubota,
  • Hideyuki Ito,
  • Michito Shimozuru
Shiori Nakamura
Hokkaido University
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Jumpei Yamazaki
Hokkaido University
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Naoya Matsumoto
Noboribetsu Bear Park
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Miho Inoue-Murayama
Wildlife Research Center, Kyoto University
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Huiyuan Qi
Wildlife Research Center, Kyoto University
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Masami Yamanaka
Shiretoko Nature Foundation
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Masanao Nakanishi
Shiretoko Nature Foundation
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Yojiro Yanagawa
Hokkaido University
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Mariko Sashika
Hokkaido University
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Toshio Tsubota
Hokkaido University
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Hideyuki Ito
Wildlife Research Center, Kyoto University
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Michito Shimozuru
Hokkaido University

Corresponding Author:shimozuru@vetmed.hokudai.ac.jp

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Abstract

Age is an essential trait for understanding the ecology and management of wildlife. A conventional method of estimating age in wild animals is counting annuli formed in the cementum of teeth. This method has been used in bears despite some disadvantages, such as high invasiveness and the requirement for experienced observers. In this study, we established a novel age estimation method based on DNA methylation levels using blood collected from 49 brown bears of known ages living in both captivity and the wild. We performed bisulfite pyrosequencing and obtained methylation levels at 39 cytosine-phosphate-guanine (CpG) sites adjacent to 12 genes. The methylation levels of CpGs adjacent to four genes showed a significant correlation with age. The best model was based on DNA methylation levels at just four CpG sites adjacent to a single gene, SLC12A5, and it had high accuracy with a mean absolute error of 1.3 years and median absolute error of 1.0 year after leave-one-out cross-validation. This model represents the first epigenetic method of age estimation in brown bears, which provides benefits over tooth-based methods, including high accuracy, less invasiveness, and a simple procedure. Our model has the potential for application to other bear species, which will greatly improve ecological research, conservation, and management.
21 Dec 2022Submitted to Molecular Ecology Resources
05 Jan 2023Submission Checks Completed
05 Jan 2023Assigned to Editor
05 Jan 2023Review(s) Completed, Editorial Evaluation Pending
07 Jan 2023Reviewer(s) Assigned
21 Feb 2023Editorial Decision: Revise Minor
14 Mar 20231st Revision Received
15 Mar 2023Submission Checks Completed
15 Mar 2023Assigned to Editor
15 Mar 2023Review(s) Completed, Editorial Evaluation Pending
20 Mar 2023Editorial Decision: Accept