Sixty year ago, Charles Elton posed that species-rich communities should be more resistant to biological invasion. However, still little is known about which processes could drive the diversity-invasibility relationship. Here we examined whether soil-microbes-mediated apparent competition on alien invaders is more negative when the soil originates from multiple native species. We trained soils with five individually grown native species, and used amplicon sequencing to analyze the resulting bacterial and fungal soil communities. We mixed the soils to create trained soils from one, two or four native species. We then grew four alien species separately on these differently trained soils. In the soil-conditioning phase, the five native species built species-specific bacterial and fungal communities in their rhizospheres. In the test phase, it did not matter for biomass of alien plants whether the soil had been trained by one or two native species. However, the alien species achieved 11.7% (95% CI: 3.7% ~ 20.1%) less aboveground biomass when grown on soils trained by four native species than on soils trained by two native species. Our results revealed soil-microbes-mediated apparent competition as a mechanism underlying the negative relationship between diversity and invasibility.

中文翻译：

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来自地下的埃尔顿多样性入侵假说的证据

六十年前，查尔斯埃尔顿提出物种丰富的社区应该更能抵抗生物入侵。然而，关于哪些过程可以驱动多样性-侵袭性关系仍然知之甚少。在这里，我们研究了当土壤来自多个本地物种时，土壤微生物介导的对外来入侵者的明显竞争是否更消极。我们用五种单独种植的本地物种训练土壤，并使用扩增子测序来分析由此产生的细菌和真菌土壤群落。我们混合土壤，从一种、两种或四种本地物种中创造出经过训练的土壤。然后我们在这些不同训练的土壤上分别种植了四种外来物种。在土壤调节阶段，五种本地物种在其根际建立了特定物种的细菌和真菌群落。在测试阶段，对于外来植物的生物量来说，土壤是由一种还是两种本地物种培育的并不重要。然而，外来物种在由四种本地物种训练的土壤上生长时的地上生物量比在两种本地物种训练的土壤上少 11.7%（95% CI：3.7% ~ 20.1%）。我们的研究结果揭示了土壤微生物介导的明显竞争是多样性和可入侵性之间负相关关系的一种机制。