Code from The island biogeography of human population size

For decades, biogeographers have sought a better understanding of how organisms are distributed among islands. However, the island biogeography of humans remains largely unknown. Here, we investigate how human population size varies among 486 islands at two spatial scales. At a global scale, we tested whether population size increases with island area and declines with island elevation and nearest mainland, as is common in non-human species, or whether humans escape such biogeographic constraints. At a regional scale, we tested whether population sizes vary among islands within archipelagos according to the positioning of different cultural source pools. Results illustrate that on a global scale, human populations increased in size with island area, similar to non-human species, yet they did not decline in size with elevation and distance to nearest mainland. At a regional scale, human population size often varied among islands within archipelagos relative to the location of different cultural source pools. Despite broad-scale similarities in the geographical distribution of human and non-human species among islands, results from this study indicate that the island biogeography of humans may also be influenced by archipelago-specific social, political and historical circumstances.

数十年来，生物地理学家（biogeographers）一直致力于深入解析生物在岛屿间的分布规律。然而，人类的岛屿生物地理学（island biogeography）研究仍在很大程度上未被探明。本研究针对两种空间尺度下486个岛屿的人口规模差异展开探究：在全球尺度上，我们检验了人口规模是否会随岛屿面积增大而增长、随岛屿海拔升高以及距最近大陆的距离增加而下降——这一规律在非人类物种中普遍存在——抑或是人类能够摆脱此类生物地理学约束；在区域尺度上，我们检验了群岛（archipelago）内部各岛屿的人口规模是否会因不同文化源地（cultural source pool）的区位差异而出现变化。研究结果显示，在全球尺度下，人类人口规模随岛屿面积增大而增长，这一点与非人类物种一致，但并未随海拔升高以及距最近大陆的距离增加而下降；在区域尺度下，群岛内部各岛屿的人口规模往往会因不同文化源地的区位差异而出现分化。尽管人类与非人类物种在岛屿间的地理分布存在大范围的相似性，但本研究结果表明，人类的岛屿生物地理学特征同时也会受到群岛特有的社会、政治与历史环境的影响。