Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 78 for “"Sexual reproduction"”.
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Strategies of Sexual Reproduction in Aphids
Die durchschnittliche Dauer der zweiten Kopulation von Uroleucon cirsii (L.) ist sowohl für Männchen als auch für Weibchen kürzer als die der ersten. Dies legt die Vermutung nahe, dass die männlichen Blattläusen zur Verfügung stehende Menge Sperma limitiert ist. Des weiteren wird Ejakulat von …
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Sexual Reproduction and Signal Transduction in the Candida Species Complex
… chapter, we use genome comparisons between parasexual, asexual, and sexual species of pathogenic <em>Candida</em> as a first approximation to answer the question of whether examining genome content alone can allow us to understand why species have a particular life cycle. We start by examining …
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Poetic genetics : family, sexual reproduction, and community in Lucretius' De rerum natura
My dissertation examines family, sexual reproduction, and community in Lucretius’ poem De Rerum Natura and reconsiders the importance of these topics in Lucretius’ formulation of Epicureanism for a Roman audience. I argue that Lucretius modifies Epicurus’ teachings about family and sex to render …
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EXPERIMENTAL STUDIES OF THE THEORIES FOR THE MAINTENACE OF SEXUAL REPRODUCTION USING SACCHAROMYCES CEREVISIAE
The existence and pervasiveness of sexual reproduction despite its many disadvantages, such as breaking up beneficial allele combinations and the cost of producing males, is an enduring question in evolutionary biology. It has yet to be determined which one, or which combination, of the …
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VEGETATIVE REPRODUCTION BY LAYERING VERSUS SEXUAL REPRODUCTION IN A SPRUCE-FIR FOREST AT ALPINE TREELINE, MEDICINE BOW MOUNTAINS, USA
… possess the ability to reproduce asexually through the vegetative process of layering. The current study investigated the frequency of vertical stems produced by layering versus seed germination within the krummholz and tree islands found across the alpine treeline ecotone. …
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DDRAD-seq based identification of genetic markers to facilitate the assessment of clonal versus sexual reproduction in dichrostachys cinerea
… via seed dispersal, the species is capable of asexual reproduction via the process of root suckering. D. cinerea can aggressively colonize grasslands and quickly becomes problematic given its ability to persist through treatments such as fire, chemical treatment and mechanical removal. Due to …
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The genomic and genetic basis of mammalian sexual reproduction : sequence of the mouse Y chromosome, and a gene regulatory program for meiotic prophase
Mammalian sexual reproduction requires sexual determination, sexual differentiation, and the production of haploid gametes. In this thesis, I examined the genomic evolution of the mouse Y chromosome, which instructs sexual determination, and genetic regulation of a program of gene expression for …
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Factors regulating transitions among life cycle phases in the marine pennate diatom <i>Pseudo-nitzschia multistriata</i>
… ('+' and '-') need to be in contact to allow sexual reproduction to occur. In this thesis, results 'are presented of an investigation using con focal and time lapse microscopy aimed at describing the different stages of the life cycle of this species. Results are also presented of various …
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The effects of clonal reproduction on population demography, genetic structure, and mating pattern of <i>Dicentra canadensis</i>
… propagules often grow near their parents, clonal reproduction can result in spatially aggregated ramets. Clustering of clones can reduce the frequency of pollen transfer between genets if pollinators tend to forage on nearby plants. In extreme cases, clustering of clones may prevent sexual …
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THE FEMALE GAMETOPHYTE: DEVELOPMENT AND FUNCTION
… gives rise to the seed after fertilization. Sexual reproduction in plants entails a series of developmental steps that culminate in the formation of the seed. The developing ovule protects the haploid female gametophyte, which is formed as the result of the megasporogenesis and …
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Distribution of chemistry and sexual fecundity in the lichenized-fungi, Xanthoparmelia cumberlandia and Xanthoparmelia coloradoensis on Boulder Mountain, Aquarius Plateau, UT
… of thallus size as an indirect measure of sexual fecundity, and the frequency of sexual reproduction.</p> <p>First, we use clustering of 46 chemicals produced by <em>X. cumberlandia</em> and <em>X. coloradoënsis</em> to evaluate the adequacy of the current taxonomic distinction between …
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Testing the Major Theories Concerning the Evolution of Sex using Experimental Evolution
The evolution of sexual reproduction has been dubbed "the queen of problems in evolutionary biology". While there is a large amount of theory about the evolution of sex, there is relatively little well controlled empirical data. This thesis is an attempt to use an experimental evolution based …
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The population genetics of Festuca rubra on park grass
An explanation for the ubiquity of sexual reproduction remains elusive although it is commonly suggested that sex and recombination facilitate a more rapid response to environmental change than clonal reproduction. If this suggestion is true then one would expect the frequency of sexual …
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Optimising fungicide application tactics: using mathematical modelling to understand qualitative and quantitative fungicide resistance management
… epidemiology, including between-season pathogen sexual reproduction. Previous modelling studies of Septoria neglected pathogen sexual reproduction, for simplicity, despite evidence that sexual reproduction is an important part of Septoria’s life cycle. We use the quantitative resistance model to …
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Population Genetic Structure of the Temperate Scleractinian Coral, Oculina Arbuscula, in Coastal Georgia
… branching morphology is conducive to asexual reproduction by fragmentation. To address this hypothesis, I combined data from allozyme electrophoresis, histocompatibility assays, and despersion of established colonies. Results indicated substantial local recruitment maintained primarily …
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The role of RNAi genes in Neurospora crassa post-transcriptional gene silencing
… life cycle with two distinct phases. During sexual reproduction, a surveillance system called Meiotic Silencing by Unpaired DNA, or MSUD, inspects all of the chromosomes from both parents for any genes out of place. When an unpaired gene is found, it signals that there might be an invader …
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How Clonal Ants Clone: The Reproductive Biology of the Clonal Raider Ant, Ooceraca Biroi
… change is affected by the mechanics of reproduction, including the number of copies of each chromosome an organism has (ploidy), whether the organism reproduces sexually or asexually, and how gametes are produced. Disentangling the rules of reproduction is therefore vital to …
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Characterization of the DMCI and Rad51 homologues and the process of meiosis in trichomonas vaginalis
<p>Trichomonas vaginal is is the sexually transmitted agent of trichomoniasis. Although the organism is believed to only reproduce via binary fission, genes specific to 5 Meiosis and Homologous Recombination have been identified in its genome. It is unclear whether the organism has the ability to …
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Effects of Various Pesticides on Hyalella Azteca
… slightly larger than females of the same age. Sexual reproduction is obligatory and occurs throughout the year in the laboratory at 21C. Young are brooded in the marsupium of the female and released before her molt. This animal is of ecological interest since it is common and abundant in a good …
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Fission Yeast Exon Junction Complex Orthologs Ensure the Maturation of Meiotic Transcripts During Meiosis
Meiosis, requisite for sexual reproduction, encompasses unique processes that do not occur in vegetative cells, including precise expression of specific genes (meiotic genes). During mitotic growth, to ensure the silencing of many constitutively transcribed meiotic genes, Mmi1-NURS (Mtl1-Red1 core) …
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