Thesis (M.A.)--University of Wisconsin--Madison, 1971. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.Sc.(Zoology)) -- University of Pretoria, 2001. / Includes bibliographical references.

No description available.

The purpose of this research was to investigate ways in which complexity could be used as the paradigm through which schoolchildren might understand ecosystems in a new way. To that end, new conceptual and practical approaches for learning about ecosystems have been presented, and the effects of these approaches on teachers and other educational stakeholders have been explored. A variety of learning environments were visited and over two hundred educational stakeholders were consulted. This resulted in a number of suggestions on and a discussion of the introduction of complexity, as a lens by which to teach about ecosystems and as a teachable subject, within that context, to pre-university schoolchildren. / The development of the learning and teaching approaches for this age group (primary and secondary school) involved exploring the state of ecosystem studies as they are presently conducted, and seeking the content within the current curricula that had congruity with the content of interest: ecosystem phenomena related to complexity. The insights gained from that investigation led to the creation of two types of approach, an approach to learning about ecosystems through the lens of complexity, and an approach to teaching about ecosystems through the lens of complexity. The Complexity Conceptual Approach deals with the various ways of understanding, or conceptualizing, ecosystem complexity and the Complexity Practical Approach deals with the content, technology, and methodology used for instruction on ecosystem complexity. The two approaches can be used together as part of a "complexity framework" that is flexible enough to be used in a diverse variety of learning situations. / Substantial consideration was given to the foreseeable prospects for these approaches: how implementation might occur, the issues involved, and the anticipated outcomes. Accordingly, topics of discussion include the introduction of the conceptual and practical approaches in terms of their effects on various educational stakeholders (such as teachers, students, parents, and administrators) and on different levels of the educational system. This type of investigation (in which potential impacts are considered) is, itself, reflective of the kind of systems-thinking that the complexity approaches were established to engender in schoolchildren.

No description available.

Elton (1927) realized that, intuitively at least, nature was complex and stable. And that the last property contributed to the first. This idea was challenged mathematically by Gardner and Ashby (1970) and May (1972), and in the years following various models have attempted to reconcile these opposing views. Unlike previous mathematical approaches that demonstrated that simple stable systems are destabilized through added complexity, the approach presented herein began with a model that was unstable. This perspective provided allows model complexity and at the same time increased likelihood of mathematically stable. This novel observation suggested that ecosystem complication might stabilize a community. Within these models a system may be stable despite the coexistence of several competitors, in direct opposition to the Competitive Exclusion Principle. The hypothesis that the principle may not hold as an absolute generality beyond two competitors is proposed. This paradox may be explained by (1) interactions between competitors, (2) a keystone predator, or (3) a combination of the first two factors. / Graduation date: 1999

Insights gained from metapopulation and metacommunity biology indicate that the connectivity of subpopulations and communities by species dispersal can profoundly impact population dynamics, community structure, and ecosystem attributes. Recent advancements in metacommunity theory further suggest that the rate of species dispersal among local communities can be important in altering local and regional species richness and ecosystem functioning. The role of species dispersal rates relative to patch-type heterogeneity and associated intrinsic community structuring mechanisms (competition, predation) in affecting diversity of multi-trophic communities, however, remains unknown. Here, I address the relative influence of regional and local processes in altering species richness and ecosystem functioning at multiple spatial scales in freshwater pond metacommunities. In a series of experiments, I employed pond mesocosm metacommunities to manipulate planktonic species dispersal rates and the incidence of top predators which differed in prey selectivity. The consequences of dispersal and predation to zooplankton species richness, trophic structure, ecosystem stability, and prey traits were evaluated. Generally, my findings support predictions from metacommunity models, and demonstrate that dispersal strongly affects community and ecosystem-level properties. In accord with dispersal-diversity theory, dispersal rate affected species richness and ecosystem stability at multiple spatial scales. The presence, but not the rate, of dispersal had strong effects on the partitioning of biomass amongst producers, grazers, and top predators. The relative influence of predation on local and metacommunity structure varied across experiments and largely depended upon predator identity and the degree of feeding specialization. The research presented herein is some of the first work to evaluate how species dispersal rates can affect dispersal-diversity relationships, diversity-stability relationships, trophic structure, and the distribution of prey traits in metacommunities. In addition to advancing ecological theory, the results have important implications for conservation as fragmented landscapes become increasingly prevalent, and local and regional biotas modified. Ultimately, it proves critical to identify drivers of local and regional species richness in order to maintain biotic integrity at the global scale. / text

Thesis (Ph. D.)--Auburn University, 2008. / Abstract. Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--Washington State University, August 2009. / Title from PDF title page (viewed on July 31, 2009). "Department of Entomology." Includes bibliographical references.