Figure 2

Evenness of bacterial coexistence through time. Lines represent mean diversity measured as the complement of the Simpson Index ± SE at 14°C (A) and 28°C (B) for communities with no phage (red), phage SBW25Φ2 (blue), phage PP7 (green) and both phage (yellow). The complement of the Simpson Index is a useful measure as it takes into account both species richness and evenness. Bacterial species richness did not vary between populations (i.e., 2 species); therefore changes in the Simpson Index here represent changes in the evenness of the community. In a community of two competing species, high values (0.5) indicate that the two species are coexisting equitably, as the community becomes increasingly dominated by a single species, so this measure tends towards 0.