Environmental heterogeneity predicts global species richness patterns better than area

Aim: It is widely accepted that biodiversity can be determined by niche-relate processes and by pure area effects from local to global scales. Their relative importance, however, is still disputed, and empirical tests are still surprisingly scarce at the global scale. We compare the explanatory power of area and environmental heterogeneity as a proxy for niche-related processes as drivers of native mammal species richnessworldwide and with biogeographical regions. Location: Global Time Period: Data was collated form the IUCN (2013) Major Taxa Studied: All mammal species, including possibly extinct species and species with uncertain presence. Methods: We developed a random walk algorithm to compare the explanatory power of area and environmental heterogeneity on native mammal species richness. As measures for environmental heterogeneity, we used elevation and precipitation ranges, which are well known correlates of species richness. Results: We find that environmental h...研究目标：学界普遍认为，从局地到全球尺度下，生物多样性可由生态位相关过程（niche-related processes）与纯面积效应共同决定。然而二者的相对重要性仍存在争议，且全球尺度上的实证检验仍极为匮乏。本研究对比了面积与作为生态位相关过程替代指标的环境异质性（environmental heterogeneity），二者作为全球范围内及各生物地理区内本土哺乳动物物种丰富度驱动因子的解释效力。 研究范围：全球 时间范围：数据整合自世界自然保护联盟（IUCN, 2013） 研究类群：所有哺乳动物物种，包括可能已灭绝及存在存疑的物种。 研究方法：本研究开发了随机游走算法（random walk algorithm），用以对比面积与环境异质性对本土哺乳动物物种丰富度的解释效力。本研究选取海拔范围与降水范围作为环境异质性的衡量指标，二者均为已知的物种丰富度关联因子。 研究结果：本研究发现环境异质性的