Protist dispersal

Foissner, W. (2006). Biogeography and dispersal of micro-organisms a review emphasizing protists. Acta Protozoologica 45,111-136. 

Thus, there is hardly any need to enlarge this subject again (for recent reviews, see Dolan, 2005 Martiny et al., 2006 Foissner, 2006, 2008 Caron, 2009). In contrast, little attention has been paid to the reasons why certain species are cosmopolitan and others are not, as evident from the reviews just cited. Wilkinson (2001) and Smith et al. (2008) suggested size and/or air currents as important dispersal factors. However, this has been abandoned by Foissner (2008). He emphasised that microfungi, mushrooms, mosses and ferns are not cosmopolitan although their dispersal means, the spores, are very abundant and usually less than 100 pm in size, corresponding to the trophic and cystic size of most protists (but see Chapters 8-12). 

Usually, live protists are very fragile. Thus, it is reasonable that dispersal occurs mainly in the cystic state (see section 5.2.2). Nonetheless, dispersal in the active state is possibly also rather common, especially in marine environments, where... 

All the data and hypotheses reviewed above, and many more not mentioned, are in conflict with a simple fact (Foissner, 2006, 2008 Fig 5.2 see also Chapters 9-12) mushrooms, mosses, ferns, lichens and horsetails have restricted distributions although their distribution means (spores) are produced in masses and in the size of most protists (< 100 pm). Further, hundreds of bacterial and fungal pests had regional or continental distribution before they were dispersed by humans. This is why I believe that, for example, air currents and the size of the organisms have little influence on their distribution. This has been supported by a study on microscopic fungi (Taylor et al., 2006). Actually, we do not know the amount of stable populations established by dispersal in the active state. Based on the data discussed above, step-by-step distribution of both, in active and cystic states, may play a significant role in at least the euryoecious species and if many similar habitats occur in a certain region. 

Table 5.3 Percentages of dispersal routes of protists. Based on the calculation of Foissner...

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