Fig. 1.

Structurally anisotropic environments arrest genetic phase separation in two-species systems, resulting in long-term coexistence. Panels depict snapshots from simulations of two-species competition in structurally isotropic (Top) and anisotropic (Bottom) environments, with color intensity reflecting species abundance, and pillars shown in gray. Time is measured in doubling times. Under isotropic conditions, domain coarsening robustly leads to extinction of one of the species. Anisotropic environments, however, allow for local pinning of competition interfaces, resulting in arrest of domain coarsening and thereby sustained coexistence. Simulation parameters are L/(1.29 λ) = 100, P = 0.1, and A_min = 0.001, with R/(1.29 λ) = 2 and Δx = 3.5 R for the anisotropic case.