Figure 2

The number of surviving species as a function of the basal grazing intensity G for various values of interspecific grazing differences (G′). Three different values of the basal birth rate are shown: (a,d) B = 1; (b,e) B = 0.75; and (c,f) B = 0.5. (a–c) The grazing intensity of a species decreases as the initial birth rate decreases, i.e., \({g}_{i}=G+G^{\prime} (20-i)\) and B_i = B−0.002(i-1) for i = 1, 2, …, s), indicating a trade-off between the birth rate and grazing intensity of a species. (d–f) The grazing intensity increases as the initial birth rate decreases, i.e., \({g}_{i}=G+G^{\prime} (i-1)\) and B_i = B−0.002(i-1) for i = 1, 2, …, s), indicating that inferior species are eaten more often by grazers. The lattice size is 100 × 100. The dispersal distance is P = 40. The initial species density is I_i = 0.03 (same for all species). The density of grazer cells is I_y = 0.4. Error bars indicate the standard deviations.