Shimozuru Michito, Nakamura Shiori, Yamazaki Jumpei, Yanagawa Yojiro, Tamatani Hiroo, Kuroe Misako, Yamazaki Koji, Koike Shinsuke, Goto Yusuke, Naganuma Tomoko, Tochigi Kahoko, Inagaki Akino, Takekoshi Naoki, Baek Seungyun, Sato Nobutaka, Honda Yusuke, Tsubota Toshio, Ito Hideyuki
Faculty of Veterinary Medicine Hokkaido University Sapporo Hokkaido Japan.
One Health Research Center Hokkaido University Sapporo Hokkaido Japan.
Ecol Evol. 2025 May 6;15(5):e71424. doi: 10.1002/ece3.71424. eCollection 2025 May.
Age is an essential factor to understand the life history and demographic parameters of wildlife. Previously, we established an age estimation method for brown bears based on blood DNA methylation level. In this study, we first applied the brown bear-specific age estimation model to other bear species, including Asian black, polar, sun, and Andean bears. Using blood DNA, we performed bisulfite pyrosequencing to determine the methylation levels at four cytosine-phosphate-guanine (CpG) sites adjacent to a single gene, . The best model specific to brown bears estimated their ages with satisfactory accuracy, with mean absolute error (MAE) of 1.5, 2.1, 2.2, and 0.4 years for Asian black (52 samples from 16 captive and 36 wild bears), polar (27 samples from 21 captive bears), sun bears (11 samples from 8 captive bears), and Andean bears (one captive bear), respectively. Then, we established an Asian black bear-specific age estimation model and a common age estimation model applicable for other bear species (i.e., a pan-bear model) using the methylation levels of the four CpG sites. The best model specific to Asian black bears had high accuracy with MAE of 1.1 after leave-one-out cross-validation (LOOCV). In addition, the best pan-bear model achieved accuracy with MAE of 1.3, 1.2, 2.1, and 2.2 years after LOOCV for brown, Asian black, polar, and sun bears, respectively. The results suggested that the pan-bear age estimation model using the aging marker (CpG sites adjacent to ) is a simple, highly accurate, and cost-effective tool that is applicable to Ursidae.
年龄是了解野生动物生活史和种群统计学参数的一个重要因素。此前，我们基于血液DNA甲基化水平建立了一种棕熊年龄估计方法。在本研究中，我们首先将棕熊特异性年龄估计模型应用于其他熊种，包括亚洲黑熊、北极熊、马来貘和安第斯熊。我们使用血液DNA进行亚硫酸氢盐焦磷酸测序，以确定单个基因附近四个胞嘧啶-磷酸-鸟嘌呤（CpG）位点的甲基化水平。针对棕熊的最佳模型以令人满意的准确度估计了它们的年龄，对于亚洲黑熊（来自16只圈养熊和36只野生熊的52个样本）、北极熊（来自21只圈养熊的27个样本）、马来貘（来自8只圈养熊的11个样本）和安第斯熊（1只圈养熊），平均绝对误差（MAE）分别为1.5、2.1、2.2和0.4年。然后，我们利用这四个CpG位点的甲基化水平建立了亚洲黑熊特异性年龄估计模型和适用于其他熊种的通用年龄估计模型（即泛熊模型）。在留一法交叉验证（LOOCV）后，亚洲黑熊特异性最佳模型具有较高的准确度，MAE为1.1。此外，泛熊最佳模型在LOOCV后，对于棕熊、亚洲黑熊、北极熊和马来貘的准确度分别达到MAE为1.3、1.2、2.1和2.2年。结果表明，使用衰老标记（基因附近的CpG位点）的泛熊年龄估计模型是一种简单、高度准确且具有成本效益的工具，适用于熊科动物。
