Distribution of the genus Mallomonas (Synurophyceae) - ubiquitous dispersal in microorganisms evaluated.

The neutral dispersal model in protists was suggested as a general principle resulting in either cosmopolitan or ecologically restricted distribution of individual species. The high local diversity results in "flat" species-area curves of individual protist groups. We investigated the local and regional diversity of the genus Mallomonas in the alluvial plain of upper Luznice in the Czech Republic. About 86.5% of species previously reported from all types of freshwater biotopes within the country were found in our investigated localities. However, there was a considerable increase of species numbers in relation to the total area of available habitats on the continent and global scales. In three species found in our localities, the floristic data indicate a possible geographically restricted distributional pattern. Here, we discuss possible reasons for this phenomenon.