The Theory Of Niche Construction In Evolutionary Process And Its Spatially Simulated Researches

Evolutionary ecology is one of the important frontiers and hotspots in recent international research of theoretical ecology and evolutionary biology. The subject of this dissertation is the new focus in this field: the research on species's niche construction and its evolutionary dynamics. Niche construction refers to the capacity of organisms to modify its local important environments, consequently modifying their both biotic and abiotic sources of natural selection in their environment. The key of niche construction is the feedback between organism and environment in evolution. As a result, the evolution is the product of interacting processes of natural selection and niche construction. The classical evolutionary theory was extended with niche construction. It provides novel theoretical grounds for species adaptation and also offers the rational mechanism for explaining many ecological phenomena at different scales. Two approaches will be utilized in this dissertation. One is the differential dynamical system. I will use the phase plane analysis and numerical solution to illustrate the equilibriums and their stability of the system. The other is the simulated models in spatial ecology: cellular automaton. By the software Matlab and Mathematica, I can show the explicit graphic mode of the spatial pattern, structure and dynamics. The dissertation consists of five chapters. Chapter one summarizes the essential framework and the frontiers and development of niche construction. Chapter two discusses the effect of niche construction on polymorphism maintenance, spatial distribution and evolutionary dynamics for spatial structured population, as well as the influences of environments on polymorphism. Chapter three focus on the spatial dynamics and distribution pattern of metapopulation with time-lagged niche construction, exploring the relationships between oscillation and spatial wave, as well as time lag, niche construction and metapopulation persistence. Chapter four indicates the effects of niche construction on metapopulation dynamics, persistent condition and threshold by modifying the destroyed habitat. In the last chapter, I make the main conclusions and the perspectives about the niche construction development. Among of them, I extend the two-locus population genetics model with spatial scale, discuss the coupled function of time lag and niche construction on metapopulation dynamics and the modification of niche-constructing populations for destroyed habitat in a creative way. The terms of occupancy momentum and occupancy inertia in the metapopulation are also first coined in the thesis. Fifteen results and conclusions are obtained in this dissertation. (1)Niche construction can lead to stable coexistence of diverse genotypes in spatially structured population, which supports a stable polymorphism even without heterozygote superiority. (2)With habitat deterioration, niche construction accelerates the formation of steady polymorphism and hence impedes the harmful influences of environment on the population, which might embody a life-history strategy of organism under the unfavorable environment. (3)Niche construction results in the coexistence with alternative polymorphism through genotype-environment feedback and limited gene flow. (4)The niche-constructing organism is an active force to alter its environment and hence the direction of natural selection in order to better survival. (5)Spatial dynamics and distribution pattern of metapopulation are profoundly influenced by time-lagged niche construction. (6)Metapopulation size can reach a fixed level in the recency effect and equal weighting of time lag but is statistical stability in primacy effect, which implies the primacy effect is most remarkable. (7)The increment in the relative weightingof each generation' niche construction and the length of time lag are significant factors for system destabilization. (8)Moderate capacity of positive niche construction benefits the metapopulation persistence. (9)The narrowing of niche breadth can decrease the metapopulation size and thereby increase the extinction risk. (10)The coupled function of time lag and niche construction make the system oscillation and generate the spiral wave, spiral-broken and circular wave in heterogeneous habitat. (ll)The spatial distributions of metapopulation and resource content are complementary due to a phase lag of their both frequencies. (12)Metapopulation persistence with niche construction depends not only on the balance between colonization and extinction, but also on the balance between the ability of niche construction and natural dissipation of habitat. (13)Metapopula-tion can survive under certain condition when the percent of suitable patches in habitat is lower than the ration of extinction to colonization. (14)Two thresholds exist in the process of transition of habitat quality dynamics from unsuitable to suitable, which include the intensity of niche construction and the initial condition of system. (15)Metapopulation size is positive correlated with the ability of positive niche construction, which means that organism or population who has strongly positive influences on their environment plays an important role to maintain the available habitat. In the dissertation, the researches on niche construction are expanded from gene level to the levels of population and metapopulation with an attribute of spatial structure and their evolutionary and ecological responses to differently spatial patterns are also discussed. We innovates in the theoretical patterns of niche construction in evolutionary process and its spatially dynamic simulation, the results of which develop theoretically and enrich methodologically the theory of niche construction.