Figure 1.
Calculation of available patches for simple food webs.
The webs are ordered from left to right by their connectance. The grey bars illustrate the spatial co-distribution of species. The length of the bars depicts the equilibrium spatial occupancy and the superposition with other species in the co-distribution.
Table 1.
Summary statistics (mean ± SE) for the empirical (n = 175) and permutated webs.
Figure 2.
Effects of A) connectance, B) diversity, and C) colonization rate on persistence for webs generated with the niche model and random structures.
Each point represents 100 replicated simulations. Parameters are: A) c = 0.2, = 0.05,
= 0.05, total diversity = 75 species with 5 primary producers; B) c = 0.2,
= 0.05,
= 0.05, connectance = 0.1 and the proportion of primary producers over total diversity is 0.2; C)
= 0.05,
= 0.05, total diversity = 75 species with 5 primary producers and connectance = 0.01.
Figure 3.
The relationship between A) Connectance, B) total species diversity, C) primary producer diversity and persistence for empirical webs.
Each point represents 100 replicated simulations with colonization rate c = 0.2 and extinction rates = 0.05 and
= 0.05. The empirical webs are distinguished for the studies in which they were compiled: Cohen = ref. 49 Dunne = ref. 54 Havens = ref. 53.
Figure 4.
Comparison of persistence between randomized and empirical webs.
Parameters are the same as in Fig. 3. A) Within-row randomization (predators); B) Within-column randomization (prey). The straight line represents a 1∶1 relationship.