Spatial patterns in microscopic organisms: new scenario in biogeography?

All organisms studied so far denote patterns, structures and peculiarities in their geographical distribution. That is so obvious that the analysis of these patterns is the field of biogeography and macroecology. Apparently, organisms smaller than 2 mm, with easily dispersed dormant propagules, seem to be without any spatial structure, cosmopolitan and without limiting factors in their distribution. This ubiquity assumption has been challenged and recent empirical evidence may show a new picture emerging for microscopic animals. They show spatial patterns in their distribution at all scales, and can thus be used as an empirical system to test principles of biogeography.