Soil biota can determine plant invasiveness, yet biogeographical comparisons of microbial community composition and function across ranges are rare. We compared interactions between Conyza canadensis, a global plant invader, and arbuscular mycorrhizal (AM) fungi in 17 plant populations in each native and non-native range spanning similar climate and soil fertility gradients. We then grew seedlings in the greenhouse inoculated with AM fungi from the native range. In the field, Conyza plants were larger, more fecund, and associated with a richer community of more closely related AM fungal taxa in the non-native range. Fungal taxa that were more abundant in the non-native range also correlated positively with plant biomass, whereas taxa that were more abundant in the native range appeared parasitic. These patterns persisted when populations from both ranges were grown together in a greenhouse; non-native populations cultured a richer and more diverse AM fungal community and selected AM fungi that appeared to be more mutualistic. Our results provide experimental support for evolution toward enhanced mutualism in non-native ranges. Such novel relationships and the rapid evolution of mutualisms may contribute to the disproportionate abundance and impact of some non-native plant species.

土壤生物群可以确定植物的入侵性，但跨范围的微生物群落组成和功能的生物地理比较很少见。我们在跨越相似气候和土壤肥力梯度的每个原生和非原生范围内的 17 个植物种群中比较了全球植物入侵者Conyza canadensis和丛枝菌根 (AM) 真菌之间的相互作用。然后，我们在温室中种植来自本地范围的 AM 真菌的幼苗。在球场上，康尼萨植物更大，更肥沃，并且与非本地范围内更密切相关的AM真菌类群的更丰富群落相关。在非本地范围内更丰富的真菌类群也与植物生物量呈正相关，而在本地范围内更丰富的类群似乎是寄生的。当两个范围的种群在温室中一起生长时，这些模式仍然存在。非本地人群培养了更丰富、更多样化的 AM 真菌群落，并选择了似乎更具共生性的 AM 真菌。我们的结果为在非本地范围内向增强的互惠关系进化提供了实验支持。这种新颖的关系和共生关系的快速演变可能导致某些非本地植物物种的丰度和影响不成比例。