Do closely related plants host similar arbuscular mycorrhizal fungal communities? A meta-analysis

The arbuscular mycorrhizal symbiosis is a widespread symbiosis in terrestrial biomes with functional implications for the ecology of both plants and soil organisms. We here asked whether phylogenetic host specificity (PHS) in arbuscular mycorrhizal (AM) fungal communities exists. Data were retrieved from the online database MaarjAM and AM fungal sequences were clustered into taxa to allow us to compute community similarity indices. The phylogenetic reconstruction of the plant hosts allowed us to obtain an objective index of host relatedness. PHS was assessed through mixed effects linear models with community similarity as dependent variable, host relatedness as independent variable and with ecosystem type as covariate. To our surprise not only did we not find evidence of PHS, but we detected evidence that more closely related plants hosted more dissimilar AM fungal communities. Results differed for different ecosystems. We highlight the importance of ecosystem type when assessing PHS. Moreover, we argue for potential causes of the unique PHS patterns that are detected in the AM association.