Output of occurrence data on brachiopod genera of a query to the Paleobiology Database on December 3rd, 2016

Geographic range is used as a correlate of extinction risk for extant and extinct organisms across the fields of conservation and paleobiology. However, the exact method used to measure geographic range, the biases, and the limitations of each are rarely discussed explicitly despite their potential to impact conclusions. Here I examine and quantify properties of five commonly used measures of geographic range (convex hull area, maximum pairwise great circle distance, latitudinal range, longitudinal range, and cell count) along with a rarely used measure (minimum spanning tree distance) in the context of three datasets. A simulated dataset of two shapes with known areal limits, a paleontological occurrence dataset of pre-Cenozoic brachiopod genera from the Paleobiology Database (PBDB), and 50000 occurrence records of birds species in the western hemisphere from the eBird database.在保护生物学与古生物学领域，地理范围常被用作衡量现生及已灭绝生物灭绝风险的关联指标。然而，尽管各类地理范围测量方法及其潜在偏倚与局限可能对研究结论产生显著影响，但相关细节却鲜有被明确讨论的情况。本研究针对三类数据集，对五种常用地理范围测量指标（凸包面积（convex hull area）、最大成对大圆距离（maximum pairwise great circle distance）、纬度跨度（latitudinal range）、经度跨度（longitudinal range）、单元格计数（cell count））以及一种极少使用的最小生成树距离（minimum spanning tree distance）的属性展开检验与量化分析。这三类数据集分别为：具备明确面积边界的双形状模拟数据集、源自古生物数据库（Paleobiology Database, PBDB）的前新生代腕足动物属古生物出现记录数据集，以及来自eBird数据库的西半球50000条鸟类物种出现记录数据集。