Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK.
School of Biological Sciences, University of Bristol, Bristol, UK.
Parasit Vectors. 2023 Oct 25;16(1):384. doi: 10.1186/s13071-023-05959-y.
The ticks Ixodes ricinus and Dermacentor reticulatus are two of the most important vectors in Europe. Climate niche modelling has been used in many studies to attempt to explain their distribution and to predict changes under a range of climate change scenarios. The aim of this study was to assess the ability of different climate niche modelling approaches to explain the known distribution of I. ricinus and D. reticulatus in Europe.
A series of climate niche models, using different combinations of input data, were constructed and assessed. Species occurrence records obtained from systematic literature searches and Global Biodiversity Information Facility data were thinned to different degrees to remove sampling spatial bias. Four sources of climate data were used: bioclimatic variables, WorldClim, TerraClimate and MODIS satellite-derived data. Eight different model training extents were examined and three modelling frameworks were used: maximum entropy, generalised additive models and random forest models. The results were validated through internal cross-validation, comparison with an external independent dataset and expert opinion.
The performance metrics and predictive ability of the different modelling approaches varied significantly within and between each species. Different combinations were better able to define the distribution of each of the two species. However, no single approach was considered fully able to capture the known distribution of the species. When considering the mean of the performance metrics of internal and external validation, 24 models for I. ricinus and 11 models for D. reticulatus of the 96 constructed were considered adequate according to the following criteria: area under the receiver-operating characteristic curve > 0.7; true skill statistic > 0.4; Miller's calibration slope 0.25 above or below 1; Boyce index > 0.9; omission rate < 0.15.
This comprehensive analysis suggests that there is no single 'best practice' climate modelling approach to account for the distribution of these tick species. This has important implications for attempts to predict climate-mediated impacts on future tick distribution. It is suggested here that climate variables alone are not sufficient; habitat type, host availability and anthropogenic impacts, not included in current modelling approaches, could contribute to determining tick presence or absence at the local or regional scale.
蓖子硬蜱和红缘革蜱是欧洲最重要的两种蜱虫媒介。气候生态位模型已被广泛应用于许多研究中，试图解释它们的分布并预测在一系列气候变化情景下的变化。本研究的目的是评估不同气候生态位模型方法解释欧洲蓖子硬蜱和红缘革蜱已知分布的能力。
构建并评估了一系列使用不同输入数据组合的气候生态位模型。从系统文献检索和全球生物多样性信息设施数据中获得的物种出现记录经过不同程度的细化，以消除采样空间偏差。使用了四种气候数据源：生物气候变量、世界气候、TerraClimate 和 MODIS 卫星衍生数据。检查了八个不同的模型训练范围，并使用了三种建模框架：最大熵、广义加性模型和随机森林模型。结果通过内部交叉验证、与外部独立数据集的比较和专家意见进行验证。
不同建模方法的性能指标和预测能力在每个物种的内部和之间都有显著差异。不同的组合能够更好地定义这两个物种的分布。然而，没有一种方法被认为完全能够捕捉到物种的已知分布。当考虑内部和外部验证的性能指标平均值时，根据以下标准，考虑了 96 个构建模型中的 24 个模型来描述 I. ricinus 的分布，11 个模型来描述 D. reticulatus 的分布：接收者操作特征曲线下的面积>0.7；真实技能统计>0.4；米勒校准斜率在 0.25 以上或以下 1；博伊斯指数>0.9；遗漏率<0.15。
这项全面的分析表明，没有一种单一的“最佳实践”气候建模方法可以解释这些蜱虫物种的分布。这对尝试预测气候对未来蜱虫分布的影响具有重要意义。这里建议，气候变量本身并不足以确定；在当前建模方法中不包括的生境类型、宿主可用性和人为影响，可能有助于确定局部或区域范围内的蜱虫存在与否。
