Department of Environmental Systems Science, ETH Zurich, Zurich, Switzerland.
Department of Biodiversity, Macroecology & Biogeography, University of Gottingen, Göttingen, Germany.
Commun Biol. 2022 Nov 10;5(1):1209. doi: 10.1038/s42003-022-04133-x.
Island biogeography has classically focused on abiotic drivers of species distributions. However, recent work has highlighted the importance of mutualistic biotic interactions in structuring island floras. The limited occurrence of specialist pollinators and mycorrhizal fungi have been found to restrict plant colonization on oceanic islands. Another important mutualistic association occurs between nearly 15,000 plant species and nitrogen-fixing (N-fixing) bacteria. Here, we look for evidence that N-fixing bacteria limit establishment of plants that associate with them. Globally, we find that plants associating with N-fixing bacteria are disproportionately underrepresented on islands, with a 22% decline. Further, the probability of N-fixing plants occurring on islands decreases with island isolation and, where present, the proportion of N-fixing plant species decreases with distance for large, but not small islands. These findings suggest that N-fixing bacteria serve as a filter to plant establishment on islands, altering global plant biogeography, with implications for ecosystem development and introduction risks.
岛屿生物地理学经典上侧重于物种分布的非生物驱动因素。然而，最近的研究强调了互利共生的生物相互作用在构建岛屿植物群中的重要性。有限的专门传粉者和菌根真菌的出现被发现限制了海洋岛屿上植物的定植。另一个重要的互利共生关系发生在近 15000 种植物和固氮（N-固定）细菌之间。在这里，我们寻找证据表明固氮细菌限制与它们相关联的植物的建立。在全球范围内，我们发现与固氮细菌相关联的植物在岛屿上不成比例地代表性不足，下降了 22%。此外，在岛屿上发生固氮植物的可能性随着岛屿的隔离而降低，而在存在固氮植物物种的情况下，随着岛屿的距离增加，大岛屿而不是小岛屿的固氮植物物种比例降低。这些发现表明，固氮细菌是岛屿植物建立的过滤器，改变了全球植物生物地理学，对生态系统发展和引入风险具有重要意义。
