Introduction The Nile monitor ( Varanus niloticus ) is the largest lizard native to Sub-Saharan Africa along the Nile River. The species inhabits a wide variety of habitats including woodlands, grasslands, mangroves, and swamps. Although the practice is not common in the Lake Tana Biosphere Reserve, the species is being hunted in Sahelian Africa for its leather, food, and pet trade. Consequently, the species is listed under the Convention on International Trade in Endangered Species. Methodology Data collection was based on onsite GIS aided presence recording. Each record of the species was first vetted for data quality. A multicollinearity analysis was conducted before fitting the MaxEnt model to the 19 bioclimatic variables. Since it provides good coverage for Africa, the Hadley Global Environment Model 2-Atmosphere Ocean (HadGEM2-AO) model was used for extracting future climate scenarios. The implementation of change factor was to correct the modeled mean climate from the climate models. The jackknife test was selected to measure the contribution of each environmental predictor variable. Area under the curve of the receiver operating characteristic was used to evaluate the performance of MaxEnt model. Results On average 2750 individuals of Nile monitor were recorded within the Lake Tana Biosphere Reserve. Mean annual temperature, precipitation and temperature were the most important predictors that limit the potential distribution of Nile monitor in the area. Most of the suitable habitats of Nile monitor were mainly predicted in the northern parts of Lake Tana. The ecological niche model produced an average AUC of 0.85. Notable records of the species were found in the vicinity of the lake and the nearby wetlands. Future projection of potential suitable areas revealed that the currently available suitable area to Nile monitor will decline in both 2050 and 2070 under both RCP 6.5 and RCP 8.5, of which the decline in suitable area under the business as usual scenario is the greatest. Conclusion The potential distribution map for Nile monitor in the Lake Tana Biosphere Reserve can help in planning land use management around its existing habitat range, discover new populations or set priorities to restore its natural habitat for more effective conservation. Extensive reductions in the amount of suitable areas under future climate scenarios suggest that the species may become threatened in future if effective conservation measures are not implemented.

中文翻译：

---

使用 MaxEnt 模型，埃塞俄比亚塔纳湖生物圈保护区现在和未来对尼罗河监测器（Varanus niloticus）的适用性

介绍 尼罗河巨蜥（Varanus niloticus）是最大的蜥蜴，原产于尼罗河沿岸的撒哈拉以南非洲。该物种栖息在各种栖息地，包括林地、草原、红树林和沼泽。虽然这种做法在塔纳湖生物圈保护区并不常见，但该物种在萨赫勒非洲地区因其皮革、食品和宠物贸易而被猎杀。因此，该物种被列入《濒危物种国际贸易公约》。方法论 数据收集基于现场 GIS 辅助存在记录。该物种的每条记录都首先经过数据质量审查。在将 MaxEnt 模型拟合到 19 个生物气候变量之前进行了多重共线性分析。由于它为非洲提供了良好的覆盖范围，Hadley 全球环境模型 2-大气海洋 (HadGEM2-AO) 模型用于提取未来的气候情景。变化因子的实施是对气候模型中模拟的平均气候进行修正。选择折刀测试来测量每个环境预测变量的贡献。接收者操作特征曲线下面积用于评估 MaxEnt 模型的性能。结果 塔纳湖生物圈保护区内平均记录了 2750 条尼罗河监测个体。年平均气温、降水量和气温是限制尼罗河监测点在该地区潜在分布的最重要预测因子。尼罗河巨蜥的大部分适宜栖息地主要预测在塔纳湖北部。生态位模型产生的平均 AUC 为 0.85。在湖泊附近和附近的湿地中发现了该物种的显着记录。未来对潜在适宜区域的预测显示，在 RCP 6.5 和 RCP 8.5 下，2050 年和 2070 年尼罗河监测的当前可用适宜区域将下降，其中在一切照旧的情景下适宜区域的下降幅度最大。结论 塔纳湖生物圈保护区尼罗河监测器的潜在分布图有助于围绕现有栖息地范围规划土地利用管理、发现新种群或确定优先事项以恢复其自然栖息地以进行更有效的保护。