Distinct biogeographic patterns in Glomeromycotinian and Mucoromycotinian arbuscular mycorrhizal fungi across China: A meta-analysis

Fine root endophytes, recently reclassified as Mucoromycotinian arbuscular mycorrhizal fungi (M-AMF), are now recognized as functionally important as Glomeromycotinian AMF (G-AMF). However, little is known about the biogeography and ecology of M-AMF and G-AMF communities, particularly on a large scale, preventing a systematic assessment of ecosystem diversity and functioning. Here, we investigated the biogeographic assemblies and ecological diversity patterns of both G-AMF and M-AMF, using published 18S rDNA amplicon datasets and associated metadata from 575 soil samples in six ecosystems across China. Contrasting with G-AMF, putative M-AMF were rare in natural/semi-natural sites, where their communities were a subset of those in agricultural sites characterized by intensive disturbances, suggesting different ecological niches that they could occupy. Spatial and environmental factors (e.g., vegetation type) significantly influenced both fungal communities, with soil total‑nitrogen and mean-annual-precipitation being the strongest predictors for G-AMF and M-AMF richness, respectively. Both groups exhibited a strong spatial distance-decay relationship, shaped more by environmental filtering than spatial effects for M-AMF, and the opposite for G-AMF, presumably because stochasticity (e.g., drift) dominantly structured G-AMF communities; while the narrower niche breadth (at community-level) of M-AMF compared to G-AMF suggested its more susceptibility to environmental differences. Furthermore, co-occurrence network links between G-AMF and M-AMF were prevalent across ecosystems, and were predicted to play a key role in stabilizing overall communities harboring both fungi. Based on the macroecological spatial scale datasets, this study provides solid evidence that the two AMF groups have distinct ecological preferences at the continental scale in China, and also highlights the potential impacts of anthropogenic activities on distributions of AMF. These results advance our knowledge of the ecological differences between the two fungal groups in terrestrial ecosystems, suggesting the need for further field-based investigation that may lead to a more sophisticated understanding of ecosystem function and sustainable management.