Researches On Spatial-structured Models And Mechanisms Of Two Basic Problems In Sex Ecology

Spatial ecology and sex ecology are both important fields in the international research of theoretical and mathematical ecology, especially the combination of those is one of the frontiers and hotspots in ecology. However, almost all papers that focus on spatial ecology have ignored the sex reproduction in population, and the research on sex often do not take the spatial factors into account. In this PhD thesis, the effect of spatial structure on the two basic problems in sex ecology, the stability of 1:1 sex ratio and the coexistence of sexual and asexual modes of reproduction, are considered. Ordi-nary differential equations, Pair-approximation and computer simulation model (Cellu-lar Automaton) are used to built spatial structured models, with the help of which we can find how the spatial structure influence on the upon two problems. Two approaches are used, mathematical analysis and numerical simulation. Meanwhile, the effect of migration on the two system are also investigated. The main results are as follows:1. The stability of 1:1 sex ratio may be strongly enhanced by the Allee effect. The effect became more severe when the spatial structure is considered explicitly.2. The small scale of ecological interactions will lead to female biased EMS;3. The impact on female and male are not the same when the spatial scale becomes larger. Male becomes more aggregated, but female more discreted. The increase of spatial scale also causes male sex local ratio decreasing, while has no effect on female local sex ratio.4. Migration does no effect on EMS, but can largely change the spatial-temporary dynamic:migration of male increases the local sex ratio, which are benefit for the growth of the population, while the migration of female decreases the local sex ratio and has no influence on the population. in addition, male local sex ratio is always greater than the ratio of female-locality, this may because females want more opportunities to mate with males.5. spatial dynamics can be essential for explanting the coexistence of Genogenesis and the sexual species which offers sperm. coexistence may occurs in two sit-uation:1. Niche differentiation and mate discrimination keep local extinction rate low, most patches contain both species; 2. In metapopulation, the system re- sembles host-parasite dynamics where parasite frequently drive the host locally extinct, and host reinvade the empty patches again.6. The good colonization rate of Genogenesis is not always beneficial for its persis-tence. The high colonization rate can cause extinction of the whole metapopula-tion.7. The effect of colonization rate of sexual patches by Genogenesis and the extinc-tion rate of patches with both species on the spatial distribution of the metapop-ulation are not the same in the two coexistence regions. So it is worth paying attention when the field study is done.8. When the effect of Genogenesis on sexual species is intermediate, high Genogenesis-only extinction can increase the equilibrium frequency of patches that Genogenesis is able to occupy.9. When the spatial interaction scale is small, Genogenesis tend to be more aggre-gated. 10. Both migration can be beneficial for Genogenesis, and destructive for sexual species. However, the influence of migration of Genogenesis are much stronger than that of sexual, The asymmetric effect is determined by the parasite feature of genogenesis.In all, Our research has enriched and developed the theories in spatial sex ecology, and enriched content that the effect of migration on spatial-temporal dynamics in metapop-ulation.