Fig. 1From: Proteobacteria explain significant functional variability in the human gut microbiomeShotgun metagenomic data show a very strong mean-variance relationship. The log10(mean) is plotted against log10(variance) for each gene family (points) in each study (headings). Bacterial ribosomal proteins (green), aminoacyl-tRNA charging genes (orange), and genes annotated to the T3SS-dependent Salmonella pathogenesis signature in KEGG (blue) are highlighted. Trend lines show a Poisson (dashed blue line) and a negative binomial (dashed red line) fit to the count data. Negative binomial provides a better fit in all three data setsBack to article page