Fig. 3: Variability between replicate communities increases during ~400 generations, yet remains significantly non-random.

A Variability in community composition between replicate communities is quantified by the mean Euclidean distance of each replicate from the medoid replicate normalized to the maximal distance between two communities composed of n species (\(\sqrt{n}\)). Blue and orange lines and shaded-areas are the medians and interquartile ranges across all pairs and trios, respectively. Dots denote the variability of specific communities across replicates. B Variability at generation ~400 against ~70, measured as the mean distance from medoid normalized to the maximal distance between two communities composed of n species (\(\sqrt{n}\)). Each dot represents a pair (blue) or a trio (orange). C Distribution of repeatability scores of the experimental data (38 pairs, 31 trios) and a random null model. The repeatability score is the frequency of replicates in which the same species increased its abundance by the biggest factor between generation ~70 and ~400. Communities that had missing replicates and therefore had less than 3 replicates for either generation ~70 or ~400, were removed from this analysis. The brown boxes represent the distribution of 2000 iterations of a shuffled model, where the values of changes in relative abundances between generation ~70 and ~400 of all species are pooled and are subsequently randomly assigned (for pairs and trios separately) to any species in any community in the dataset. Boxes indicate the quartiles and whiskers are expanded to include values no further than 1.5X interquartile range. *p value = 0.05, **p value <0.005. P values indicate the frequency of iterations were the shuffled data’s mean repeatability score was at least as high as the experimental data’s mean. Source data are provided as a Source Data file.