By stochastic simulation, we investigate the spatial pattern in the biological system composed of three competing species. Topological defects are introduced to explain the pattern formation in this system. The spatial dimension d determines the nature of defects such as kinks, vortices, and strings. When d=2,3, the system approaches the stationary state, where the peculiar defect configuration is found.

• Received 1 August 1989

DOI:https://doi.org/10.1103/PhysRevLett.63.2688