Notes. The numbers are averages over the 12 runs of each layer. The column “Number of fusion events” includes events with and without mutualism. The other columns focus exclusively on fusion events with mutualism. By design, all fusion events in Layer 4 Mutualism are cases of mutualism. The expected number of fusion events is prob_fusion × num_generations × pop_size = 100, but fusion is suppressed by the limits max_area_first and max_area_last in Layer 4 and Layer 4 Shuffled, and fusion is further suppressed by the requirement of mutual benefit in Layer 4 Mutualism.