Diversity and Geographic Distribution of Free-Living Heterotrophic Flagellates - Analysis by PRIMER

Data on the distribution of approximately 350 species of heterotrophic flagellates (protozoa) in 31 communities from sites around the world - inclusive of marine and freshwater habitats, water column and benthic habitats, and 'extreme' (i.e. anoxic and hypersaline) habitats - are analysed by the Cluster algorithm in the PRIMER package. We have sought to minimise the impact of factors extrinsic to the actual distribution of organisms which may distort our perception of the geographic patchiness of organisms. In our analyses, communities from areas which are geographically close to each other do not cluster together. Communities from similar habitats cluster together (i.e., water column communities group together, as do benthic communities, or freshwater and marine communities), and communities from more unusual habitats segregate from those of less 'extreme' habitats. We argue that our capacity to draw robust conclusions on the distribution of these organisms is hampered by under-reporting. We favour a model in which there are relatively few species of free-living heterotrophic flagellates, and that most of these species have a cosmopolitan distribution.