Author(s): Rotenberry, JT; Balasubramaniam, P | Abstract: © 2020 The Authors. Ecography published by John Wiley a Sons Ltd on behalf of Nordic Society Oikos Connecting the geographical occurrence of a species with underlying environmental variables is fundamental for many analyses of life history evolution and for modeling species distributions for both basic and practical ends. However, raw distributional information comes principally in two forms: points of occurrence (specific geographical coordinates where a species has been observed), and expert-prepared range maps. Each form has potential short-comings: range maps tend to overestimate the true occurrence of a species, whereas occurrence points (because of their frequent non-random spatial distribution) tend to underestimate it. Whereas previous comparisons of the two forms have focused on how they may differ when estimating species richness, less attention has been paid to the extent to which the two forms actually differ in their representation of a species’ environmental associations. We assess such differences using the globally distributed avian order Galliformes (294 species). For each species we overlaid range maps obtained from IUCN and point-of-occurrence data obtained from GBIF on global maps of four climate variables and elevation. Over all species, the median difference in distribution centroids was 234 km, and median values of all five environmental variables were highly correlated, although there were a few species outliers for each variable. We also acquired species’ elevational distribution mid-points (mid-point between minimum and maximum elevational extent) from the literature; median elevations from point occurrences and ranges were consistently lower (median −420 m) than mid-points. We concluded that in most cases occurrence points were likely to produce better estimates of underlying environmental variables than range maps, although differences were often slight. We also concluded that elevational range mid-points were biased high, and that elevation distributions based on either points or range maps provided better estimates.

中文翻译：

---

将物种的地理分布与环境变量联系起来：范围图与观察到的发生点

作者：Rotenberry，JT；Balasubramaniam, P | 摘要：© 2020 作者。由 John Wiley a Sons Ltd 代表北欧社会 Oikos 出版的生态学 将物种的地理分布与潜在的环境变量联系起来，对于许多生活史进化分析以及为基本和实际目的建模物种分布至关重要。然而，原始分布信息主要有两种形式：发生点（观察到某个物种的特定地理坐标）和专家准备的范围图。每种形式都有潜在的缺点：范围图往往高估了一个物种的真实出现，而出现点（因为它们频繁的非随机空间分布）往往低估了它。虽然之前对这两种形式的比较集中在估计物种丰富度时它们可能如何不同，但较少关注这两种形式在表示物种环境关联方面的实际差异程度。我们使用全球分布的禽类鸡形目（294 种）来评估这种差异。对于每个物种，我们将从 IUCN 获得的范围图和从 GBIF 获得的发生点数据叠加在四个气候变量和海拔的全球地图上。在所有物种中，分布质心的中值差异为 234 公里，所有五个环境变量的中值高度相关，尽管每个变量都有一些物种异常值。我们还从文献中获得了物种的海拔分布中点（最小和最大海拔范围之间的中点）；点出现和范围的中位海拔始终低于（中位数 -420 m）低于中点。我们得出的结论是，在大多数情况下，发生点可能比范围图对潜在环境变量产生更好的估计，尽管差异通常很小。我们还得出结论，高程范围中点偏高，基于点或范围图的高程分布提供了更好的估计。我们得出的结论是，在大多数情况下，发生点可能比范围图对潜在环境变量产生更好的估计，尽管差异通常很小。我们还得出结论，高程范围中点偏高，基于点或范围图的高程分布提供了更好的估计。我们得出的结论是，在大多数情况下，发生点可能比范围图对潜在环境变量产生更好的估计，尽管差异通常很小。我们还得出结论，高程范围中点偏高，基于点或范围图的高程分布提供了更好的估计。