Abstract
Although animals and plants in tropical rainforests are known to be hyperdiverse within and between communities, it is unknown if similar patterns are reflected at the microbial scale with unicellular eukaryotes or protists. Using environmental DNA sequencing of soils sampled in rainforests from Costa Rica, Panama, and Ecuador, we found that the Apicomplexa dominated the protist communities; these parasites potentially promote animal diversity in the forests by reducing population growth rates in a density-dependent manner similar to the Janzen-Connell hypothesis for tropical trees. Extremely high OTU diversity and high OTU turnover between samples within the same forests suggest that protists, not arthropods, are the most diverse eukaryotes in tropical rainforests, and that rainforest soil protists are at least as diverse, and potentially more diverse, than those in the marine plankton.
