Fig. 1

Increasing dilution causes striking shifts in a three-species community. a To probe how added mortality changes community composition, we cocultured three soil bacteria over a range of dilution factors. Cells were inoculated and allowed to grow for 24 h before being diluted into fresh media. This process was continued for 7 days, until a stable equilibrium was reached. The magnitude of the dilution factor (10–10⁶) determines the fraction of cells discarded, and thus the amount of added mortality. b We began with a three-species community (Enterobacter aerogenes (Ea), Pseudomonas citronellolis (Pci), and Pseudomonas veronii (Pv)), initialized from four starting fractions at each dilution factor. The outcomes of two of the starting fractions are shown (see Supplementary Fig. 8b for remaining starting fractions), along with a subway map, where survival of species is represented with colors assigned to each species. Black dots indicate where data were collected, while colors indicate the range over which a given species is inferred to survive. Species Pv dominates at the lowest dilution factor, and Ea dominates at the highest dilution factors. The grouping of two colors represents coexistence of two species, whereas the two levels at dilution factor 10³ indicate bistability, where both coexisting states, Ea–Pv and Ea–Pci, are stable and the starting fraction determines which stable state the community reaches. Error bars are the SD of the beta distribution with Bayes' prior probability (see “Methods”). Source data are provided as a Source Data file