Dynamics Of A Three-species Food Web Model With Omnivory

This thesis mainly studies the dynamics of a three-species food web model with omnivory.Omnivory,defined as feeding on more than a single trophic level,is ubiquitous in nature.In a constantly changing environment omnivory does also vary.The previous theory focuses only on the topology of food web about the variation of omnivory,however it may also have an influence on the top predator’s growth pattern at the same time.Usually omnivores are generalists which can utilize a variety of prey resources.To consider that,we firstly develop a three-species food web model with the omnivory parameter for describing the changing process of omnivory that the top predator transform from generalists to specialists,which can only thrive best in a narrow range of environmental conditions.Secondly,for investigating the relationship between omnivory and the stability of food webs,we explore the complex global dynamics analytically and numerically,such as the bistability,Hopf bifurcation,and chaotic behavior.It is shown that omnivory can be either stabilizing the food web model at the low degree of omnivory or causing the extinction of intermediate predator at the high degree of omnivory.In the end,the future research project of omnivory will be presented.