Mean co-habitation (population) levels of environments occupied by bacteria of a given lifestyle. Annotations of lifestyle are according to  (specialized, obligatory symbionts, aquatic, multiple, faculatative symbionts, and terrestrial) and according to identification of species in environmental samples (human gut; see Materials and methods). The number of environments in each lifestyle (in the same order as in the figure) are 11, 81, 5, 144, 157, 38, and 117 (environments can include species of more than a single lifestyle). Error bars show the standard error.
Freilich et al. Genome Biology 2009 10:R61 doi:10.1186/gb-2009-10-6-r61