Simulated Research On Spatial Eco-epidemiology

Eco-epidemiology is a newly emerged cross discipline and now has been the frontiers and hotspots in the research of mathematical biology. The subject of this dissertation is the spatial eco-epidemiology, which is a new focus of this field. Spatial eco-epidemiology has extended and enriched the research of population and community epidemiology. It provides novel theoretical grounds for endangered species suffering a disease with the environmental changes and habitat destruction. Combined with spatial technology, it has provides deep ecological mechanisms for disease transmission at different scales. We firstly summarize the concept, theory, frontiers and development of eco-epidemiology in detail, and then discuss the theories and models in spatial eco-epidemiology. Secondly, based on the eco-epidemiological model where the predator suffering the epidemic, we investigate the complex dynamics due to Allee effect, and the effects of spatial scale, habitat loss and demographic stochasticity on the spatiotemporal dynamics of the epidemic transmission. Thirdly, we reveal how the spatial landscape heterogeneities due to habitat loss affect the invasion, transmission and distribution patterns in host-parasite epidemic system, and illustrate the relation between the two components of spatial heterogeneities. Finally, we construct the host-parasite-predation eco-epidemiologic model, and study primarily the effects of habitat loss with different spatial configuration on the dynamics of eco-epidemiologic system, and also explore the interal biological mechanism of eco-epidemiology. Among of them, the extension with eco-epidemiological model on predator-prey interactions at spatial scale, and discussion the effects of spatial structure of habitat loss on eco-epidemiological systems both are innovative works. Two approaches will be utilized in this dissertation. One is the differential dynamical system, such as pair approximation. I will use the phase plane analysis and numerical solution to illustrate the equilibriums and their stability of the system. The other is constructing the spatially explicit simulation, and then to achieve the explicit graphic mode of the spatial pattern, structure and dynamics, which can make up for the deficiency of spatially implicit model. We have obtained the following new results: (1) Allee effect is a stabilizing or a destabilizing force in ecological systems could be determined by its intensity. (2) The infection rate and predation rate both are the key factors which affecting the spatial patterns of species in the eco-epidemiological systems. (3) Mean-field assumption, local interaction and demographic stochasticity have great influence on the disease invasion and distribution patterns. (4) Spatial scale of interactions between individuals affects complexly the spatiotemporal dynamics of epidemic transmission. With increasing of neighborhood size, the infected force become stronger and form aggregated spreading wave. (5) At a certain range, habitat loss and its spatial structure can benefit the control of the epidemic disease, which indicates the possibility of using human disturbance in habitat as a potential epidemic-control method in conservation. (6) Not only the quantity of habitat loss but also the spatial correlations of patch types caused by nonrandom habitat loss affect the invasion and transmission of disease. More fragmented landscape (high amount of habitat loss, low clustering of lost patches) hinders the parasitic infection, which also indicates that whether the spatial heterogeneity benefits or hinders the invasion is dependent on the considered ecological process. (7) Two components of the spatial heterogeneity (the amount and spatial autocorrelation of the lost habitat) form a trade-off in determining the host-parasite dynamics. (8) Within a certain range of habitat loss, host can counterbalance the positive and negative effects, and shows a rising tendency. (9) The epidemic is more likely to break out in the prey-predator system if only a small amount of habitat loss. (10) A highly aggregated distribution of species is a common behavioral strategy when dealing with habitat loss or other environmental stresses. (11) The parasite-host/prey-predator eco-epidemiological systems have the similar mechanism with the intraguild predation systems, and the predator acts as the intraguild predation, the infected prey acts as intraguild prey, and the susceptible prey acts as shared resource. (12) Species at the highest trophic level are no longer affected the most by habitat loss, which depend not only on the biological mechanism but also on the external environmental disturbances.