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 21 for “"chromosome evolution"”.
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Chromosome evolution in Lepidoptera
… all animals, plants and fungi is organised into chromosomes. While each species tends to have a fixed number of chromosomes in their genome, chromosome numbers vary widely across the tree of life. Changes in chromosome number occur due to rearrangements, such as the fusion and fission of …
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Sex Chromosome Evolution in Blow Flies
… closely related species, indicative of rapid evolutionary rates. Sex chromosome karyotypes are generally conserved within families; however, many species have derived sex chromosome configurations. Insects display a plethora of sex chromosome systems due to rapid diversification caused by …
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Molecular analysis of sex chromosome evolution in papaya
Sex chromosomes are of great interest due to their role in sexual reproduction. Sex chromosomes evolve through the suppression of recombination in the sex determining region between the X and Y chromosomes which allows for each region to evolve and change independently. Papaya’s trioecious sex is …
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Dissecting the evolutionary forces shaping sex chromosome evolution in papaya
The human Y chromosome is an ancient relic of its autosomal precursor; most of the genes have been lost in its 166 million years of separation from the X, and it has drastically shrunken in size. The highly degenerated nature of the human sex chromosomes make it impossible to trace the events that …
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Chromosome evolution and mechanisms of speciation in the Anopheles gambiae complex
… Anopheles mosquito species. Understanding the chromosome evolution and mechanisms of speciation can shed light on developing novel ecological-friendly vector control techniques. Sibling species of the An. gambiae complex provide an excellent model system for these topics. To understand the …
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Chromosome evolution in Rhabditina (Nematoda) with a focus on programmed DNA elimination
… enabled research on the mechanisms that shape chromosome evolution in diverse taxa. My thesis focuses on nematodes from the Rhabditina suborder, which exhibit a high rate of chromosome rearrangement and have several species with chromosome-level assemblies available for comparison. To study …
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Molecular phylogenetics, systematics, reproductive safeguarding and chromosome evolution of the genus Lachenalia (Asparagaceae: Scilloideae)
… establishing a solid framework for downstream evolutionary studies. A dated version of the multi-locus phylogenetic tree is employed here to test the hypothesis that pollen limitation, resulting from a low abundance of insect pollinators, promotes the evolution of reproductive safeguarding …
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Sex chromosome evolution of papaya: Dynamic structural and expression changes and identification of associated traits
Sex chromosomes are found throughout many diverse lineages across the animal and plant kingdom. Most of the sex chromosomes that have been studied are well established and have already experienced many evolutionary forces, making it difficult to reconstruct the dynamic changes involved in the …
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Polyploidy inference across time scales in the charismatic carnivorous plant genus Drosera L. (Droseraceae, Caryophyllales)
… I sought to evaluate methods for detecting chromosome number changes of different types and ages, and to develop Drosera as a system for chromosome evolution. This was achieved by using chromosome evolution models to test different rates of chromosome evolution between different subgenera in …
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Genomic dissection of structural variations and evolution forces of the sex chromosomes in spinach (spinacia oleracea)
Sex chromosomes evolved independently and repeatedly animals and plants. Although considerable differences existed among diverse lineages in terms of sexual dimorphism and genetic basis of sex determination, the underlining principles and evolutionary forces that lead to the formation and …
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Evolutionary history of the canary grasses (Phalaris, Poaceae)
… historic hybridization, polyploidy events, and chromosome evolution in the grasses. This body of research presents the first molecular phylogenetic and phylogeographic reconstruction of the genus based on the nuclear ITS and plastid trnT-F DNA regions allowing species relationships and the …
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Isolation and Genomic Analysis of the Cetacean Y-chromosome
The male-specific mammalian Y-chromosome represents a powerful tool for studying malemediated gene flow and genome evolution. Here it was possible to identify 7 polymorphic microsatellites for the first time in an odontocete species, using a combination of cell culture, cytogenetics and molecular …
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Sequence characterization of the HSA12/22/12 evolutionary breakpoint region on SSC5q21
The HSA12/22/12 evolutionary breakpoint region on SSC5q21 has been sequenced, further localized, and preliminarily characterized. The existence and location of the breakpoint regions were originally determined in the human-porcine comparative map constructed by Meyers and colleagues. Bacterial …
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Functional characterization and analysis of Carica papaya SHORT VEGETATIVE PHASE (CpSVP)
… in papaya is controlled by a pair of nascent sex chromosomes with two slightly different Y chromosomes that distinguish males (XY) and hermaphrodites (XYh). These two Y chromosomes diverged about 4,000 years ago with only 0.4% sequence difference between them. The hermaphrodite specific region of …
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The generation and maintenance of diversity in a rapid adaptive radiation
… fishes are a pre-eminent example of adaptive evolutionary radiation. The diversity of species (nearly 1000 extant) is mirrored by an array of variation in dozens of phenotypes (e.g. trophic morphology, tooth shape, color patterns, behavior, development). The unique characteristics of this …
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Chromosomes and spermatozoa of the great apes and man
The chromosome complement of four species phylogenetically related to man, the chimpanzee (Pan troglodytes), the pygmy chimpanzee (Pan paniscus), the gorilla (Gorilla gorilla), and the orangutan (Pongo pygmaeus) have been analysed with chromosome banding techniques and compared to the human …
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Genomic analysis of sex chromosomes and sex differentiation in Caricaceae
… study mechanisms for sex determination and sex chromosome evolution in plants, due to the presence of three sex types: female, male, and hermaphrodite. Previous research has revealed the location of the sex determination region (SDR) and the existence of three sex chromosomes X, Y, and Yh in the …
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Chromosome and Genome Evolution in Culicinae Mosquitoes
… studying their population structure, and evolution can help to facilitate the development of new strategies for vector control. Studies on Aedes albopitcus as well as on species from the Culex pipiens complex, which are widely spread in the United States, provide excellent models on these …
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