Fig. 4: Effect of within-species evolution.

A Degradation percent or (B) population size (log₁₀CFU/ml) of each species on day 3 in three conditions: the ancestral strains before the experiment, strains harvested after 18 rounds of selection treatment (S) and after 18 rounds of the random control treatment (R). Data from mono- (alone) and pairwise co-cultures are shown (with partner). Significant differences are calculated using a generalized linear model with biological replicate as random variable and number of species in culture as an explanatory variable, significant p-values with a Bonferroni correction for multiple comparisons are shown. Treatment only had a significant effect on Ct (detailed statistics in main text). C–E Interactions between ancestral species (C), the species evolved in the random treatment (D) and the selection treatment (E) defined as the log₂ fold-change of the focal species in CFU/ml of day 3 in co-culture with the companion species vs mono-culture. Interactions that were not significant (no significant difference between growing alone or with companion species) are shaded, p-values were adjusted using the Benjamini-Hochberg method. Positive (facilitative) interactions are in blue, while negative interactions are shown in red. White squares are ones that we did not measure. Overall, we saw very few changes between ancestral and evolved species (black-bordered squares, quantified in Table S2). Species abbreviations are as listed in Table 1.