Arbuscular mycorrhizal communities on islands worldwide. Island AMF

Island biogeography theory is one of the most influential paradigms in ecology. That island characteristics, including remoteness, can profoundly modulate biological diversity has been borne out by studies of animals and plants. By contrast, the processes influencing microbial diversity, life history traits and functions in island systems are largely unknown. We sequenced arbuscular mycorrhizal (AM) fungal DNA from plant roots collected on 13 islands worldwide and compared AM fungal diversity on islands with existing data from mainland sites. AM fungal communities on islands were as diverse as mainland communities and diversity was maintained even on the remotest islands (< 6000 km from the closest mainland). Nonetheless, AM fungal communities on distant islands comprised a higher proportion of ruderal taxa and taxa with large spores, indicating that establishment of AM fungi on distant islands may require tolerance of significant environmental stress. Largely in contrast to patterns recorded for macro-organisms, efficient long-distance dispersal favours certain functional traits and outweighs endemism and extinction in shaping island communities of AM fungal diversity.