Figure 5. Opening the system through migration leads to functional convergence.

(A) Replicate communities all started from the same inoculum (and the same inoculum as in Figure 2) were assembled in an open system with global migration (N = 93)—that is, in addition to the normal transfer, each community received a small amount of migrants from a common migrant pool or with migration from the regional pool (i.e., inoculum) (N = 92) (STAR Methods). Communities were assembled under these migration scenarios for twelve growth cycles (T1–T12), after which migration was stopped, and communities were allowed to stabilize for six additional transfers without migration (T13–T18).

(B) Community composition at Transfer 18. ESVs with a relative abundance ≤0.01 are shown as “other”.

(C) R/F ratio of the communities at Transfer 18 for the no migration (Figure 2B), global migration, and regional migration (Figure 5B) treatments. Each dot represents a community and is colored by its taxonomic community state. The blue dots show communities mainly composed of fermenters, the yellow dots show communities where Alcaligenes is the dominant respirator, and the purple dots show communities where Pseudomonas is the dominant respirator. The gray shading area represents the interquartile range of the communities shown in Figure 1A.