Showing papers by "Pejman Rohani published in 1995"
TL;DR: It is demonstrated that parasitoid searching efficiency is highest (and mean host densities lowest) for levels of aggregation where the spatial dynamics consist of an even mixture of spirals and disordered patterns, and that spatial transitions are also reflected in the temporal dynamics.
Abstract: Recent studies of host-parasitoid metapopulations have shown how uniform dispersal, from a patch to its neighbouring patches, can result in the persistence of an otherwise non-persistent interaction. Here these models are extended to include density-dependent parasitoid aggregation. The fraction of dispersing hosts colonize the neighbouring patches equally, whereas parasitoid dispersal is related to the relative density of healthy hosts in each surrounding patch. Interestingly, this shows that the degree of parasitoid aggregation is associated with the self-organization of spatial structures and, in particular, spiral waves. Regions where spirals are most pronounced correspond to minimal variance in population densities. It is demonstrated, however, that parasitoid searching efficiency is highest (and mean host densities lowest) for levels of aggregation where the spatial dynamics consist of an even mixture of spirals and disordered patterns. Using an algorithmic complexity measure, it is verified that spatial transitions are also reflected in the temporal dynamics. Finally, it is demonstrated that multiple episodes of parasitoid dispersal, within a host generation, can inhibit persistence, particularly for large parasitoid movement rates.
72 citations
TL;DR: In this article, the stability properties of this model hinge solely on A and ft, as shown in Fig. 1 a. The model is expressed as a Coupled Map Lattice formalism (Kaneko 1993).
Abstract: N, +, = N,(1 + aN,). eqn 1 Here N is the population density in successive generations, t and t+ 1, A is the finite rate of increase of the population, and a and # are constants defining the density-dependent survival. The stability properties of this model hinge solely on A and ft, as shown in Fig. 1 a. Bascompte & Sole (henceforth referred to as 'B&S') applied this model to a grid or array of local populations which they linked with dispersal to four nearest neighbours, with the aim of exploring how such spatial structure affects the population dynamics. Using the Coupled Map Lattice formalism (Kaneko 1993), they express their model as:
63 citations
TL;DR: In this paper, a simple population model was presented that exhibits both the period-doubling and the quasi-periodic routes to chaos with the variation of a single parameter, and the relative robustness of the two routes against structural perturbations in the form of added immigration terms was compared.
41 citations
1 citations