Age estimation based on blood DNA methylation levels in brown bears

Area of Science:

• Wildlife Ecology
• Genetics
• Conservation Biology

Background:

• Accurate age estimation is crucial for wildlife ecology and management.
• Conventional tooth cementum annuli analysis in bears is invasive and requires expertise.
• There is a need for less invasive and more accessible age estimation techniques.

Purpose of the Study:

• To establish a novel, non-invasive age estimation method for brown bears using DNA methylation.
• To compare the accuracy of this epigenetic method against traditional techniques.

Main Methods:

• Collected blood samples from 49 known-age brown bears (captive and wild).
• Analyzed DNA methylation levels at 39 CpG sites across 12 genes using bisulfite pyrosequencing.
• Developed a predictive model based on methylation levels correlated with age.

Main Results:

• DNA methylation levels near four genes significantly correlated with bear age.
• A model using methylation at four CpG sites near the SLC12A5 gene achieved high accuracy (MAE of 1.3 years, MedAE of 1.0 year).
• This represents the first epigenetic age estimation method for brown bears.

Conclusions:

• The novel DNA methylation-based method provides an accurate, less invasive alternative to tooth analysis for brown bear age estimation.
• This epigenetic approach simplifies age determination and has potential applications for other bear species.
• Improved age estimation can significantly benefit wildlife research, conservation, and management strategies.