Extended Data Fig. 2: Expected and observed niche expansion, double niche expansion, and niche contraction per species.

Expected cases were calculated by randomly assigning events (10⁴ times) across species and carbon sources. Bar plots show the number of cases, in which each species is (a) at least one of the two auxotrophic partners that experience niche expansion (green), (b) involved in cases in which both auxotrophic partners experience niche expansion (green), or (c) at least one of the two auxotrophic partners that experience niche contraction (red) in coculture. The vertical light gray and black bar in (a) shows the fraction of cases, where the species experience or induce niche expansion. Asterisks indicate the results of a binomial test comparing expected and observed values (* P < 0.05, ** P < 0.01, *** P < 0.001).