cific mutualisms. P. Natl. Acad. Sci. U.S.A. 95, 8676-8680. [23] Durrett, R., 1988. Lecture Notes on Particle Systems and Percolation. Wadsworth & Brooks/Cole Advanced Books & Software, Stamford, CT. [24] Durrett It, Levin SA, 1994. Stochastic spatial models: a user's guide to ecological applications. Philos. T. Roy. Soc. B, 343,