Figure 8

Pattern in ordination of compositions from single body site admits of multiple explanations. Left: Jensen-Shannon PCoA of MetaHIT stool samples, showing a characteristic ‘U’ shape that has been observed in many independent studies. Colors indicate three hypothesized enterotypes, which we do not discuss here. Reproduced with permission from Figure 3 of Ref. ³⁰. Right: Jensen-Shannon PCoA of simulated samples from Body Site 1 under two different levels of dispersal limitation. In the first (top), each community was initialized with 2,500 randomly chosen species out of the regional pool of 5,000. The communities display a continuous gradient in the population size of the most abundant species (over all samples) along the ‘u’ shape from one end to the other. In the second (bottom), each community started with 4,900 species. These communities display a continuous gradient of environmental conditions along the ‘U’ shape from one end to another.