Accounting for environmental variation in co-occurrence modelling reveals the importance of positive interactions in root-associated fungal communities

• Published in: Molecular Ecology
• Main Authors: Abrego, Nerea, Roslin, Tomas, Huotari, Tea, Tack, Ayco J. M., Lindahl, Bjorn D., Tikhonov, Gleb, Somervuo, Panu, Schmidt, Niels Martin, Ovaskainen, Otso
• Other Authors: Department of Agricultural Sciences, Research Centre for Ecological Change, Plant Production Sciences, Spatial Foodweb Ecology Group, Organismal and Evolutionary Biology Research Programme, Otso Ovaskainen / Principal Investigator
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2021
• Subjects: Arctic; co-occurrence; endophyte; interaction network; mycorrhiza; symbiotic network; ARBUSCULAR MYCORRHIZAL FUNGI; ECTOMYCORRHIZAL FUNGI; MICROBIAL INTERACTIONS; SPECIES COOCCURRENCE; ELEVATION GRADIENT; PLANT-GROWTH; DIVERSITY; COMPETITION; ENDOPHYTES; BACTERIA; 1181 Ecology; evolutionary biology; 11832 Microbiology and virology
• Online Access: http://hdl.handle.net/10138/326715

Understanding the role of interspecific interactions in shaping ecological communities is one of the central goals in community ecology. In fungal communities, measuring interspecific interactions directly is challenging because these communities are composed of large numbers of species, many of which are unculturable. An indirect way of assessing the role of interspecific interactions in determining community structure is to identify the species co-occurrences that are not constrained by environmental conditions. In this study, we investigated co-occurrences among root-associated fungi, asking whether fungi co-occur more or less strongly than expected based on the environmental conditions and the host plant species examined. We generated molecular data on root-associated fungi of five plant species evenly sampled along an elevational gradient at a high arctic site. We analysed the data using a joint species distribution modelling approach that allowed us to identify those co-occurrences that could be explained by the environmental conditions and the host plant species, as well as those co-occurrences that remained unexplained and thus more probably reflect interactive associations. Our results indicate that not only negative but also positive interactions play an important role in shaping microbial communities in arctic plant roots. In particular, we found that mycorrhizal fungi are especially prone to positively co-occur with other fungal species. Our results bring new understanding to the structure of arctic interaction networks by suggesting that interactions among root-associated fungi are predominantly positive. Peer reviewed