Fig. 2. Dynamics of a five-species community described by a symmetrical interaction network such that S1 > S2, S3; S2 > S3, S4; ; S5 > S1, S2 where “>” indicates overgrowth. Initially all species have identical growth rates, and the likelihood of a species Si overgrowing Sj (as defined by the interaction matrix) is unity. However, at 500 generations a shift in the “environment” is introduced. In (A) the growth rate of S5 drops to 75% of that of S1-S4, whereas in (B) growth rates are unaffected but the interaction between S1 and S2 becomes reversible such that S1 wins in 60% of cases whereas S2 wins in 40% of cases. S1 = light blue; S2 = yellow; S3 = red; S4 = dark blue; S5 = green. Bold lines (green in A, light blue in B) indicate species analyzed to estimate CLSs (see Figs. 3, 4).