Some Consequences of Habitat Heterogeneity for Population Dynamics

The dynamic effects of spatial heterogeneity are discussed in relation to three systems: (1) a single-species system, (2) a parasitoid-host system, and (3) a disease-host system. In each case, a heterogeneous environment of discrete patches is specified, between which the animals are distributed. The central conclusion is the same irrespective of the system: the more contagious the distribution of the animals per patch, the greater is the population stability. In the single-species and disease-host systems, this arises because increased clumping accentuates the density dependent mortality within a patch, while in the parasitoid-host system it results from differential susceptibility of host individuals to parasitism.