Dispersal of ciliated protist cysts: mutualism and phoresy on mites

The dispersal potential of a species determines its abundance, distribution, and community compatibility (biocoenosis; Kneitel and Miller 2003) but the extent and the dispersal mechanisms of many organisms, especially microbes, are largely unknown and, in some cases, based on serendipitous observations (Ptatscheck et al. 2018, Sugiura et al. 2019). The extent of dispersal depends on the type, i.e., active or passive dispersal; the latter potentially results in rather ubiquitous occurrence (Finlay 2002). Active dispersal is mainly performed by large animals (i.e., many mammals), whereas passive dispersal depends on biotic (epizoochory or endozoochory) and abiotic factors (wind, water current) that allow the dispersing organism to cover distances ranging from a few meters to several kilometers (Nkem et al. 2006, Ptatscheck et al. 2018, Sugiura et al. 2019). So far, several studies have presented various examples that show the existence of different passive dispersal mechanisms that involve active biological factors, such as those mediated by cross-kingdom (even tripartite) interactions (i.e., fungus–mites–birds, plants–fungus–insects; Ptatscheck et al. 2018, Sugiura et al. 2019).