Department of Community Ecology, Helmholtz Centre for Environmental Research-UFZ, 06120 Halle (Saale), Germany;
German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, 04103 Leipzig, Germany.
Proc Natl Acad Sci U S A. 2019 Aug 13;116(33):16436-16441. doi: 10.1073/pnas.1901954116. Epub 2019 Jul 29.
Biodiversity patterns emerge as a consequence of evolutionary and ecological processes. Their relative importance is frequently tested on model ecosystems such as oceanic islands that vary in both. However, the coarse-scale data typically used in biogeographic studies have limited inferential power to separate the effects of historical biogeographic factors (e.g., island age) from the effects of ecological ones (e.g., island area and habitat heterogeneity). Here, we describe local-scale biodiversity patterns of woody plants using a database of more than 500 forest plots from across the Hawaiian archipelago, where these volcanic islands differ in age by several million years. We show that, after controlling for factors such as island area and heterogeneity, the oldest islands (Kaua'i and O'ahu) have greater native species diversity per unit area than younger islands (Maui and Hawai'i), indicating an important role for macroevolutionary processes in driving not just whole-island differences in species diversity, but also local community assembly. Further, we find that older islands have a greater number of rare species that are more spatially clumped (i.e., higher within-island β-diversity) than younger islands. When we included alien species in our analyses, we found that the signal of macroevolutionary processes via island age was diluted. Our approach allows a more explicit test of the question of how macroevolutionary factors shape not just regional-scale biodiversity, but also local-scale community assembly patterns and processes in a model archipelago ecosystem, and it can be applied to disentangle biodiversity drivers in other systems.
生物多样性模式是进化和生态过程的结果。它们的相对重要性经常在模型生态系统中进行测试，例如海洋岛屿，这些岛屿在这两个方面都有所不同。然而，生物地理研究中常用的粗尺度数据通常没有足够的推断能力来区分历史生物地理因素（例如岛屿年龄）和生态因素（例如岛屿面积和栖息地异质性）的影响。在这里，我们使用来自夏威夷群岛的 500 多个森林样地的数据库来描述木本植物的局部尺度生物多样性模式，这些火山岛屿在年龄上相差几百万年。我们表明，在控制岛屿面积和异质性等因素后，最古老的岛屿（考艾岛和瓦胡岛）的单位面积本地物种多样性大于较年轻的岛屿（毛伊岛和夏威夷岛），这表明宏观进化过程不仅对整个岛屿的物种多样性差异，而且对当地群落组装也有重要作用。此外，我们发现较老的岛屿拥有更多空间聚集的稀有物种（即更高的岛内β多样性），而较年轻的岛屿则较少。当我们将外来物种纳入分析时，我们发现通过岛屿年龄来反映宏观进化过程的信号被稀释了。我们的方法允许更明确地测试宏观进化因素如何不仅塑造区域尺度的生物多样性，而且还塑造模型群岛生态系统中的局部尺度群落组装模式和过程的问题，并且可以应用于其他系统中分离生物多样性驱动因素。
