Simulated Research On Population Ecology:Effects Of Species Behavior And Parasites On Species Coexistence Of Intraguild Predation Systems

Understanding the relationship between diversity and stability in ecological communities is a key objective of ecological theory. Meanwhile, empirical researches have showed that intraguild predation (IGP) system is a common phenomenon in natural ecology. But theoretical studies have suggested that the coexistence of species in IGP food webs is very difficult. This contrary conclusion induces the attentions of ecologists. Meanwhile, the approaches of spatial ecology have become one of the most important tools in mathematical ecology, theoretical ecology and conservation biology. Here, based on simulation methods in spatial ecology, we have explored the species coexistence and species diversity in the spatially structured intraguild predation systems. We constructed the spatially explicit simulation models, which include couple lattice model and cellular automaton. By Matlab and NetLogo, both the spatial patterns of species distribution and species dynamics have been illustrated here. The framework of intraguild predation systems has theoretically supported the species conservation in complex food web. Combined with spatial technology, it also can provide deeply ecological mechanisms for theoretical ecology.The dissertation will be separated into four contents. First, we summarize the frontiers and development of intraguild predation systems; Second, the concepts, theories and simulation approaches of spatial ecology have been illustrated; Third, effects of species behaviours on the coexistence of spatial intraguild predation system have been showed; Finally, species coexistence and populations density in intraguild predation system affected by parasite transmission have been revealed. Based on simulation models, we obtained the following results:(1) When predation rate does not change, predator pursuit can expand coexistence range; (2) Whether prey evasion can enhance coexistence depends critically on the predation-competition relationship. Prey evasion could enhance coexistence as intraguild predator has overall advantage or weak trade-off; (3) There exists asymmetry between effects of predator pursuit and prey evasion on coexistence, where the effect of predator pursuit has more dramatic effects than prey evasion; (4) Parasite will promote species coexistence. And the density of IGpredator will increase with the competition strength as IGpredator can persist; (5) If IGpredator has intension to avoid the parasite infection, then the coexistence range will decrease; (6) As parasite impede the moving speed of infected IGprey, then the coexistence range will expand.