Fig 2. The relationship between mean relative abundance of taxa across all samples and the frequency with which they are detected in individual samples for three representative datasets.

Each dot represents a taxon and the solid line is the best-fitting neutral community expectation. The dashed lines and gray area depict the 95% confidence bands. The left panel shows a microbial community sampled from a compost as an example of an abiotic environment. The center panel shows data for the natural microbiota of C. elegans nematode populations sampled from the same compost. The right panel shows the microbiota of a wild M. musculus mouse population. Here, the red dots indicate members of the microbial family Ruminococcaceae, which are predominantly overrepresented compared with the neutral expectation. A genus that was found in much fewer mice than expected by chance is Shigella, being present in less than a quarter of the hosts despite a neutral expectation of nearly 100% prevalence. The OTU abundance data used to generate this figure are available in S6 and S7 Data. OTU, operational taxonomic unit.