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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

The spatial patterning of Hieracium pilosella invaded short tussock grasslands : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Science in Environmental Sciences in the University of Canterbury /

Dickinson, Yvette. January 2008 (has links)
Thesis (M. Sc.)--University of Canterbury, 2008. / Typescript (photocopy). Includes bibliographical references (leaves 109-118). Also available via the World Wide Web.
12

Spatial diffusion model for simulation of urban land cover change /

Wen, Yuming. January 2004 (has links)
Thesis (Ph. D.)--University of Rhode Island, 2004. / Typescript. Includes bibliographical references (leaves 146-158).
13

A spatial and temporal analysis of conifers using remote sensing and GIS

Koon, Michael. January 2004 (has links)
Thesis (M.S.)--Marshall University, 2004. / Title from document title page. Document formatted into pages; contains viii, 40 p. including illustrations. Includes abstract. Includes bibliographical references (p. 39-40).
14

Three essays on conservation-oriented community land use management /

Jiang, Yong, January 2007 (has links)
Thesis (Ph.D.) -- University of Rhode Island, 2007. / Typescript. Includes bibliographical references (leaves 189-198).
15

Spatial and temporal variability of tree transpiration and its drivers along a soil drainage gradient in the boreal black spruce forest

Angstmann, Julia L. January 2009 (has links)
Thesis (Ph.D.)--University of Wyoming, 2009. / Title from PDF title page (viewed on July 22, 2010). Includes bibliographical references.
16

A multidimensional Eulerian-Lagrangian model to predict organism distribution

Wang, Yushi. Politano, Marcela. Weber, Larry Joseph. January 2009 (has links)
Thesis supervisors: Marcela Politano, Larry J. Weber. Includes bibliographic references (p. 95-97).
17

Diversity patterns in pen shell (Atrina rigida) communities

Munguia, Pablo. Levitan, Don Miller, Thomas E. January 2006 (has links)
Thesis (Ph. D.)--Florida State University, 2006. / Advisors: Don R. Levitan and Thomas E. Miller, Florida State University, College of Arts and Sciences, Dept. of Biological Science. Title and description from dissertation home page (viewed Sept. 22, 2006). Document formatted into pages; contains xi, 110 pages. Includes bibliographical references.
18

Predation and Harvesting in Spatial Population Models

Shrader, Connor R 01 January 2023 (has links) (PDF)
Predation and harvesting play critical roles in maintaining biodiversity in ecological communities. Too much harvesting may drive a species to extinction, while too little harvesting may allow a population to drive out competing species. The spatial features of a habitat can also significantly affect population dynamics within these communities. Here, we formulate and analyze three ordinary differential equation models for the population density of a single species. Each model differs in its assumptions about how the species is harvested. We then extend each of these models to analogous partial differential equation models that more explicitly describe the spatial habitat and the movement of individuals using reaction-diffusion equations. We study the existence and stability of non-zero equilibria of these models in terms of each model's parameters. Biological interpretations for these results are discussed.
19

Spatial ecology of the serotine bat

Moussy, Caroline Maude Christine January 2013 (has links)
The spatial ecology of a species underpins an array of important questions about the ecology and evolution of a species, relating for instance to sociality, population dynamics, geographical distribution or genetic partitioning. Furthermore, the understanding of the spatial ecology of a species also has important implications for conservation and for disease management. It is in this context that I have examined the spatial ecology of the serotine bat (Eptesicus serotinus), in Europe, and especially at the northern limit of its distribution in England, using population genetic and stable isotope analyses. Data from nuclear microsatellite markers indicated higher levels of gene flow on the continent than in England. Consistent with this, England was separated into three genetically distinct populations, inter-connected by male-driven gene flow. Substantial asymmetric gene movement over the English Channel was inferred, possibly indicating a northward and westward range expansion. Mitochondrial DNA revealed fast population expansion and strong female philopatry. Moving to finer scale, δ13C in wing tissue and fur revealed that the association of individuals at roosts is flexible and dynamic, possibly reflecting their membership to communities operating at larger geographic scales. Communities of E. serotinus seem therefore to create a network of roosts with individuals continually re-assorting among themselves both within and across breeding seasons. The integration of the genetic and isotopic data highlighted complex spatial, social and temporal interactions in this species. While individual associations within communities seem to be flexible, communities were found to be strongly segregated over the breeding season. In contrast, genetic connectivity operates on a larger geographical scale than the local summer landscape. Together, these findings help explain the apparent absence in the UK of the European Bat Lyssavirus 1 (EBLV-1) for which this species is the main host. Hence, the relative fragmentation of this low-density population may inhibit the virus’ spread. However, with regular immigration from the continent, EBLV-1 could eventually enter the UK.
20

Espaço e diversificação: uma perspectiva teórica / Space and diversification: a theoretical perspective

Rossine, Fernando Welker Sapojkin 03 July 2014 (has links)
Alguns dos padrões ecológicos mais consistentemente encontrados na natureza, como as relações espécie-área e as distribuições de rank-abundância, podem ser previstas por uma classe de modelos neutros. Nesse contexto, neutralidade quer dizer que há equivalência demográfica entre os indivíduos de todas as espécies. Para os modelos dessa classe, extinções causadas por flutuações demográficas são contrabalanceadas por algum mecanismo de especiação. Cada modo de especiação deixa uma marca nos padrões ecológicos emergentes. Foi mostrado que um modelo com uma implementação mecanística de especiação gera padrões de diversidade que dependem de limites geográficos. Eu usei simulações baseadas em indivíduos com uma implementação mecanística de especiação para investigar se padrões espaciais intrínsecos das comunidades poderiam transformar os padrões de biodiversidade. Eu descobri que existe uma transição de fase no modo de especiação que depende da estrutura espacial da comunidade. Uma gama extensa de padrões encontrados na natureza puderam ser unificados em um único modelo dada essa transição de fase. Relações entre riqueza e idade de um clado podem ser melhor compreendidas considerando-se o efeito previsto de desaceleração crítica da diversificação. Uma nova interpretação foi dado ao efeito \"Clado Morto Andando\", característico dos períodos seguintes a extinções em massa. Uma redefinição objetiva e biologicamente razoável para especiação alopátrica é explorada, graças às propriedades da transição de fase descrita. Eu proponho a existência de um \"crédito de especiação\", e exploro suas possíveis implicações para a conservação a longo prazo da biodiversidade / Some of the most consistent ecological patterns encountered in nature, such as species-area relationships and rank-abundance distributions, can be predicted from a class of neutral models. In this context, neutrality means demographic equivalence between individuals of all species. Within this class of neutral models, species extinction by demographic fluctuations is counterbalanced by some speciation mechanism. Each particular speciation mode leaves an imprint in the resulting patterns. A model with a mechanistic speciation implementation was shown to generate patterns dependent on geographic constraints. I used individual based simulations with a mechanistic speciation implementation to investigate whether the intrinsic spatial patterning of organisms could transform biodiversity patterns. I found out that there is a phase transition on speciation modes that is dependent on the spatial structure of the community. An extended range of the biodiversity patterns found in nature can be unified into a single model because of this phase transition. Clade richness and age relationships may be understood by the predicted critical slowdowns in diversification. A new interpretation is given to the post mass extinction \"Dead Clade Walking\" effect. An objective and biologically reasonable redefinition of allopatric speciation is explored by exploiting the phase transition. I propose the \"speciation credit\" effect, and its potential implications for long term biodiversity conservation

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