Species arranged in a ring evolve via punctuated equilibrium. The least-fit species and its neighbors are replaced each step. Self-organized criticality produces power-law avalanche distributions.
Step: 0
Min fitness: —
Mean fitness: —
Avalanche size: —
Largest ever: —
Rule: replace min-fitness species + 2 neighbors with random values.
Critical threshold f* ≈ 2/3 (Bak & Sneppen 1993).
Avalanche = steps with min < threshold.
P(avalanche ≥ s) ~ s^{−τ}, τ ≈ 1 (SOC).