Fig. 4.

Diameters of zones of clearing for ampicillin (a) and tetracycline (b) disc diffusion assays. The diameter of the zone of clearing was measured three times for each plate and averaged for a single-plate measurement. At least eight replicate plates were measured for each monoculture and community type. The “weakest link” species (i.e., the species with the largest median zone of clearing in monoculture) is indicated on the x-axis. Pairwise comparisons of the zone of clearing for each monoculture and community was performed with a Mann–Whitney U test with Bonferroni adjustment for multiple comparisons. Significant differences are noted by different letters above each cluster; shared letters represent non-significant differences