Data from: Niche differentiation and expansion of plant species are associated with mycorrhizal symbiosis

Mycorrhizal symbiosis is a widespread association between plant roots and mycorrhizal fungi, which is thought to contribute to plant niche differentiation and expansion. However, this has so far not been explicitly tested.

To address the effect of mycorrhizal symbiosis on plants’ realized niches, we addressed how mycorrhizal status (i.e. the frequency of occurrence of mycorrhizal symbiosis), flexibility (i.e. the ability to grow both with and without mycorrhizal symbiosis) and type of a plant species affect the realized niche optima, widths and volumes. For this, we used co-occurrence data from the flora of the Netherlands along soil fertility, moisture, pH, salinity, light and temperature gradients. Phylogenetic dependency of the species was taken into account using phylogenetic generalized least squares models.

We show that facultatively and flexibly mycorrhizal plants have the widest niches compared to non-mycorrhizal and obligately mycorrhizal, and inflexible plants respectively. Among obligate plant symbionts, ecto- and ericoid mycorrhizal plants exhibited the widest niches compared to plants with other mycorrhizal types. Also, plants with different mycorrhizal statuses and types differed in their realized niche optima.

Synthesis. Our results indicate that mycorrhizal symbiosis mediates plant niche differentiation and expansion, facilitating the understanding of current distribution patterns of plant species, as well as predicting shifts in plant distribution and dominance due to environmental changes.

菌根共生（mycorrhizal symbiosis）是广泛存在于植物根系与菌根真菌之间的共生关系，被认为有助于植物生态位分化与拓展，但此前尚未得到明确验证。为探究菌根共生对植物实际生态位（realized niche）的影响，本研究旨在明确植物物种的菌根状态（mycorrhizal status，即菌根共生的发生频率）、灵活性（即同时可在有、无菌根共生条件下生长的能力）以及菌根类型，如何影响植物实际生态位的最适值、宽度与体积。为此，我们使用了荷兰植物区系沿土壤肥力、湿度、pH值、盐度、光照及温度梯度分布的共现数据，并通过系统发育广义最小二乘模型（phylogenetic generalized least squares models）控制物种间的系统发育依赖性。研究结果显示，相较于非菌根植物、专性菌根植物以及非灵活性植物，兼性菌根植物的实际生态位宽度最广；在专性植物共生体中，外生菌根与杜鹃花类菌根植物的实际生态位宽度亦显著宽于其他菌根类型的植物。此外，不同菌根状态和类型的植物，其实际生态位最适值亦存在显著差异。研究综合表明，本研究结果证实菌根共生可介导植物生态位的分化与拓展，这不仅有助于理解当前植物物种的分布格局，还可用于预测环境变化下植物分布与优势度的转变。