Population pattern repeats at the individual level with all non-farmers producing significantly fewer amoebae and spores than farmers carrying B. xenovorans in all five B. xenovorans supernatants. Farmers increase amoeba proliferation and spore production under the same conditions. We measured the change in amoeba proliferation (a) and spore production (b) in all five B. xenovorans supernatants compared with either amoeba proliferation or spore production in a buffer control using 10 clones (5 farmers and 5 non-farmers) tested against 5 B. xenovorans supernatants individually prepared from 5 farmer-associated strains. Results are displayed as individual box plots. We used data from the 3-h logarithmic growth curve time point to display the solitary-stage box plots. Tails of box plots show minimum and maximum values. See Fig. 4 for all solitary-stage time points.