Age estimation of Asian elephants (Elephas maximus) using methylation-sensitive high-resolution melting (MS-HRM)

Age is an important parameter that provides a better understanding towards biodemographic trends–development, survival, reproduction and environmental effects–which is critical for conservation. However, current methods to estimate age is difficult in many species and no standardised technique has been adopted. Here, we focus on the endangered Asian elephants ( Elephas maximus ) to examine the potential of estimating age from DNA methylation through two candidate age-related epigenetic genes and develop an age estimation model. DNA was extracted from blood samples ( n = 53) from 25 known-aged captive individuals. Methylation rates of two genetic regions: RALYL and TET2 were measured via methylation-sensitive high-resolution melting (MS-HRM) which is a labour-, time-, and cost-effective method. The developed DNA methylation-based age estimation model showed a significant correlation with chronological age for both markers: RALYL (cor = 0.54, p < 0.001) and TET2 (cor = −0.60, p < 0.001). The final age estimation model combining both genes showed a mean absolute deviation (MAD) of 5.56 years. This study highlights MS-HRM as a practical and convenient method to investigate the relationship between epigenetic modifications in age-related genes and chronological age in Asian elephants, and its potential to provide key life history information for future implications.