@article {Mah{\'e}050997, author = {Fr{\'e}d{\'e}ric Mah{\'e} and Colomban de Vargas and David Bass and Lucas Czech and Alexandros Stamatakis and Enrique Lara and David Singer and Jordan Mayor and John Bunge and Sarah Sernaker and Tobias Siemensmeyer and Isabelle Trautmann and Sarah Romac and C{\'e}dric Berney and Alexey Kozlov and Edward A. D. Mitchell and Christophe V. M. Seppey and Elianne Egge and Guillaume Lentendu and Rainer Wirth and Gabriel Trueba and Micah Dunthorn}, title = {Soil Protists in Three Neotropical Rainforests are Hyperdiverse and Dominated by Parasites}, elocation-id = {050997}, year = {2016}, doi = {10.1101/050997}, publisher = {Cold Spring Harbor Laboratory}, abstract = {Animal and plant richness in tropical rainforests has long intrigued naturalist. More recent work has revealed that parasites contribute to high tropical tree diversity (Bagchi et al., 2014; Terborgh, 2012) and that arthropods are the most diverse eukaryotes in these forests (Erwin, 1982; Basset et al., 2012). It is unknown if similar patterns are reflected at the microbial scale with unicellular eukaryotes or protists. Here we show, using environmental metabarcoding and a novel phylogeny-aware cleaning step, that protists inhabiting Neo-tropical rainforest soils are hyperdiverse and dominated by the parasitic Apicomplexa, which infect arthropods and other animals. These host-specific protist parasites potentially contribute to the high animal diversity in the forests by reducing population growth in a density-dependent manner. By contrast, we found too few Oomycota to broadly drive high tropical tree diversity in a host-specific manner under the Janzen-Connell model (Janzen, 1970; Connell, 1970). Extremely high OTU diversity and high heterogeneity between samples within the same forests suggest that protists, not arthropods, are the most diverse eukaryotes in tropical rainforests. Our data show that microbes play a large role in tropical terrestrial ecosystems long viewed as being dominated by macro-organisms.Contact: dunthorn{at}rhrk.uni-kl.de}, URL = {https://www.biorxiv.org/content/early/2016/07/27/050997}, eprint = {https://www.biorxiv.org/content/early/2016/07/27/050997.full.pdf}, journal = {bioRxiv} }