A schematic illustration of the experimental design.

Rodents were trapped in 1-ha plots (squares), representing populations of Gerbillus andersoni [(A), host individuals are represented as green rodent outlines and the populations are shaded pink], G. pyramidum [(B), purple outlines and green shading] and G. gerbillus [(C), red outlines and blue shading]. The rodent populations were part of three communities; a single host species (G. andersoni, left tan shading), two (G. andersoni and G. pyramidum, middle tan shading) or three rodent species communities (right tan shading). Bacterial lineage (rod-like shapes) diversity and composition were assessed for three organization levels (individuals, populations and communities of hosts) nested within three hierarchical spatial scales (a host individual, a plot, and a region).