Schematic placement of niches of SUP05 (blue) and Sulfurimonas/Sulfurovum-related SOB (SM/SV; green to brown) in the mixing gradient. Being placed in the steep part of the gradient, Sulfurimonas and Sulfurovum-related bacteria are exposed to higher amplitudes of variation of environmental parameters, for example, hydrogen sulfide concentrations, which leads to diversification into different species, each one with its own microniche.