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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.
1

Heterogeneous Stress Response in a Clonal Invader (Imperata cylindrica): Implications for Management

Sanford, Sarah Grace 01 January 2011 (has links)
Life history traits such as growth, survival, and clonality can vary within a population. When such variation exists in a population of an invasive species, it can affect population dynamics, and if any part of the variation has a genetic basis the population can evolve in response to control regimes. Evolutionary responses to control efforts may shift the population towards a few more resilient genotypes, or towards different types in different microenvironments, depending on the scale of gene flow with respect to the patchiness of the environment. The purpose of this study is to examine whether the application of stress similar to control efforts (light level manipulation and biomass removal) results in varying emergence, growth, and survival rates between samples taken from spatially separated patches of the invasive clonal grass Imperata cylindrica. Accelerated Failure Time (AFT) and logistic regression models were fit to survival, emergence and growth data collected from two experiments in which samples collected from four spatially separated Imperata cylindrica patches were exposed to light level manipulation and biomass removal. Patch identity plays a large role in explaining variation in time-to-emergence, time-to-death, and probabilities of emergence and survival, especially under stressed conditions. Rhizome and above ground biomass characteristics also play substantial roles in explaining variation in emergence, survival, and growth, though more so under non-stressed conditions. Our results warrant further study of heterogeneous responses to stressful conditions, especially those imposed under control and management regimes. This heterogeneity may have important impacts on population processes such as maintenance, expansion, and gene flow.
2

Evolutionary adaptations : a thesis presented in fulfilment of the requirements for the degree of Master of Arts at Massey University, Auckland, New Zealand

Murphy, Elsa Sian January 2009 (has links)
It is the contention of this thesis that the field of adaptation studies is struggling to emerge from a restrictive, outdated and static paradigmatic framework. It proposes that the field would benefit from widening its current frame of reference to include more input and perspectives from the evolutionary biological sciences. This thesis considers the implications for the study of culture of the Darwinian theory of evolution – how it might become a more integral part of how we understand culture generally, and of how we read specific texts. It attempts to re-contextualise adaptation studies within an ongoing, conceptual paradigm shift in Western culture, initiated by Darwin’s publication of his theory of evolution by natural selection. It contends that the Darwinian Revolution is far from complete within the humanities and that the time is ripe for greater consilience and exchange between the bio-sciences and humanities disciplines. This thesis explores the current state of adaptation studies as a discipline, referring in particular to recent work by adaptation theorists such as Robert Stam, Linda Hutcheon, Thomas Leitch and Julie Sanders and their efforts to reinvigorate and redirect adaptation studies. It considers how deeply ingrained, evaluative modes of thought could be holding back these efforts, and if an updated, mutable Darwinian paradigm could aid them. This thesis also speculates on the viability of an evolutionary unit of culture, the meme, and its possible relevance to adaptation studies and the wider study of culture. Finally, it applies a Darwinian perspective, on various levels, to an extensive, detailed textual analysis of the non-fiction book The Orchid Thief and the film Adaptation.

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