Species distribution modelling and predictor variables for species distribution and niche preferences of <i>Pilosocereus leucocephalus</i> group <i>s.s.</i> (Cactaceae)

Ecological niche modelling is useful in estimating the environmental requirements of species and, by extension, can also estimate their distributional areas. For most cacti, ecological niche modelling and comparisons between species have only been performed for a set of variables mainly associated with temperature and precipitation. To expand environmental predictors in addition to climate variables, we use topographic and edaphic variables. The aims of this study were to determine which environmental factors influence the geographical distribution of the <i>P. leucocephalus</i> species group <i>s.s.</i> from Mexico and Central America, to build species distribution models, and to assess whether species have different climatic preferences. Based on ecological niche modelling, the main environmental variables that contribute to the distribution of species and the similarities or differences in ecological niches between species were inferred using Maxent and ENMTools. The results revealed that the studied species had different responses to environmental variables, resulting in a unique combination of conditions for each species, showing only six environmental variables in common. In general, variables with the greatest contributions to the models were climatic, followed by edaphic and topographic variables. The results of the quantification of niches between species showed that there was less than 0.5 overlap in Schoener’s <i>D</i> values, suggesting niche divergence for the group species but in environments more similar than would be expected by random chance. Although species shared affinities for seasonally dry tropical forests, the importance of preferences for different sets of environmental variables by each species was clear. In addition, niche divergence between closely related species of the <i>P. leucocephalus</i> group <i>s.s.</i> is concordant with the previous delimitation at the species level.

生态位建模（Ecological Niche Modelling）可用于估算物种的环境需求，进而推演其分布区域。针对多数仙人掌类植物，现有生态位建模及物种间比较研究仅采用了与温度、降水高度相关的变量集。为扩充气候变量之外的环境预测因子，本研究引入了地形与土壤变量。本研究旨在明确影响产自墨西哥与中美洲的*P. leucocephalus*狭义类群（s.s.）的地理分布，构建物种分布模型，并评估不同物种是否存在迥异的气候偏好。本研究基于生态位建模，利用Maxent与ENMTools软件推断出影响物种分布的核心环境变量，以及物种间生态位的异同。研究结果显示，受试物种对环境变量的响应存在差异，每个物种均拥有独特的环境条件组合，仅共享6种环境变量。整体而言，对模型贡献度最高的变量为气候因子，其次为土壤与地形因子。物种间生态位量化结果显示，斯科纳D（Schoener’s D）值的重叠度均低于0.5，表明该类群物种存在生态位分化，但它们所处的环境仍较随机预期更为相似。尽管受试物种均偏好季节性干燥热带森林，但各物种对不同环境变量集的偏好差异依然显著。此外，*P. leucocephalus*狭义类群内近缘物种间的生态位分化，与此前基于物种水平的类群界定结果一致。

搜集汇总

背景与挑战

背景概述

该数据集聚焦于墨西哥和中美洲的Pilosocereus leucocephalus物种组（仙人掌科），通过生态位建模（使用Maxent和ENMTools工具）分析其物种分布和生态偏好。研究结合了气候、地形和土壤变量作为预测因子，结果显示物种对环境响应各异，生态位存在分化（D值小于0.5），但环境相似性高于随机预期，支持先前物种界定的有效性。