No biogeographical pattern for a rootassociated fungal species complex

Aim The biogeography of microbes is poorly understood and there is an open debate regarding if and how microbial biodiversity is structured. At the beginning of the 20th century, Baas Becking laid the foundations for the biogeography of microbes by stating that ‘Everything is everywhere, but the environment selects’ (the EisE hypothesis). This hypothesis remained dogma for almost a century. However, the recognition that microbial ‘species’ are often assemblages of reproductively isolated lineages challenged the EisE hypothesis, leading to the now common assumption that microbial communities possess cryptic biogeographic structures. We tested the presence of a cryptic biogeographical structure for a well-characterized fungal species complex (the Phialocephala fortinii s.l.–Acephala applanata species complex, PAC) using precise molecular species resolution. In addition, we analysed factors that could govern PAC community assembling.