Effects Of Species Richness And Interaction On Host Community Composition And Disease Transmission Dynamics

Parasite can play a key role in constructing biological communities through direct effects on host species or/and indirect effects on trophic networks.In recent years,it has been a hot topic in mathematical ecology to study the species survival and stability in multi-host food webs.In this thesis,three different ecological networks were constructed by using the structured network model.Based on the eco-epidemiological model,we first discuss the effects of parasite species richness and network structure on community composition.Secondly,we focus on the effect of intraguild predation(IGP)on the relationship between host diversity and disease transmission.The research content includes five chapters.In Chapter 1,the theories and research status of species interaction,diversity and disease transmission are summarized.In Chapter 2,we briefly summarize the theories and models of eco-epidemiology,and discuss the development of methods in eco-epidemiology in detail,such as common ecological network generation methods,network topological properties,basic reproduction number and diversity index in the community;In Chapter 3,we discuss the effects of parasitic richness and parasitic link structure on species survival and topological characteristics in hybrid networks(including hosts subweb and host-parasite subweb)based on the eco-epidemiological model.In Chapter 4,the effects of predation in the competitive community on the relationship between host diversity and disease transmission have been explored based the eco-epidemiological models;In Chapter 5,we summarizes and future prospects of this thesis.Through the research,the following new results have been obtained:(1)The effects of parasitic links on community structure depend on the level of parasite species richness and network structure;(2)For the host-parasite interaction network generated by inverse niche model,the standard deviation of vulnerability presents a hollow shape against the parasite species richness;(3)Although the network structure strongly affects the topological properties of multi-host parasitic food webs,the effect on species coexistence is very weak;(4)By altering the proportion of predation in a competitive community,species richness can switch from enhancing to inhibiting disease transmission dependent on predatory interactions;(5)Without IGP interactions,host species richness can weaken the "dilution effect" and enhance thedisease transmission,but IGP can generally heighten the negative diversity-disease relationship.(6)Although trait-mediated interactions(captured as the infection-induced changes in predation rate)only weakly affect disease prevalence,density-mediated interactions(captured as the additional infection-induced mortality)can pose a relatively strong influence on disease transmission.