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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

Genetic Diversity and Phylogeographic Structure of the Parasitic Plant Genus Conopholis (Orobanchaceae): Implications for Systematics and Post-glacial Colonization of North America

Rodrigues, Anuar 14 January 2014 (has links)
Parasitism in plants is often accompanied by a suite of morphological and physiological changes resulting in a condition known as the ‘parasitic reduction syndrome’. With changes including extreme vegetative reduction, frequently beyond any resemblance to its photosynthetic relatives, accompanied by significant losses of genes linked to photosynthesis, the study of parasitic plants can be challenging. Conopholis (Orobanchaceae) is a small holoparasitic genus distributed across eastern and southwestern North America and Central America. This genus has never been the subject of a molecular phylogenetic or morphometric analyses. In addition, very little is known of the relationships among populations and of their post-glacial history. To investigate the species limits and phylogenetic relationships in Conopholis, we conducted a comprehensive molecular phylogenetic study of the genus as well as a fine-scale morphometric study. Based on plastid and nuclear sequences, Conopholis was found to contain three distinct and well-supported lineages which have varying degrees of overlap with previously proposed taxa. The clustering and ordination analyses of the morphometric study corroborated the molecular data, demonstrating the morphological differentiation between the three lineages detected within Conopholis. A taxonomic re-alignment is proposed for the genus that recognizes three species, C. americana, C. panamensis, and C. alpina. To address genetic diversity and phylogeographic structure of C. americana in eastern North America, microsatellite markers were developed and characterized for the first time in this species. Using these newly generated markers along with sequences from the plastid genome, the persistence of a minimum of two glacial refugia at the last glacial maximum were inferred, one in Florida and southern Alabama and another in the Appalachian Mountains near the southern tip of Blue Ridge Mountains. The diversity seen across the southern Appalachian Mountains supports the hypothesis that populations derived from the southern and northern refugia come together in this area.
2

Genetic Diversity and Phylogeographic Structure of the Parasitic Plant Genus Conopholis (Orobanchaceae): Implications for Systematics and Post-glacial Colonization of North America

Rodrigues, Anuar 14 January 2014 (has links)
Parasitism in plants is often accompanied by a suite of morphological and physiological changes resulting in a condition known as the ‘parasitic reduction syndrome’. With changes including extreme vegetative reduction, frequently beyond any resemblance to its photosynthetic relatives, accompanied by significant losses of genes linked to photosynthesis, the study of parasitic plants can be challenging. Conopholis (Orobanchaceae) is a small holoparasitic genus distributed across eastern and southwestern North America and Central America. This genus has never been the subject of a molecular phylogenetic or morphometric analyses. In addition, very little is known of the relationships among populations and of their post-glacial history. To investigate the species limits and phylogenetic relationships in Conopholis, we conducted a comprehensive molecular phylogenetic study of the genus as well as a fine-scale morphometric study. Based on plastid and nuclear sequences, Conopholis was found to contain three distinct and well-supported lineages which have varying degrees of overlap with previously proposed taxa. The clustering and ordination analyses of the morphometric study corroborated the molecular data, demonstrating the morphological differentiation between the three lineages detected within Conopholis. A taxonomic re-alignment is proposed for the genus that recognizes three species, C. americana, C. panamensis, and C. alpina. To address genetic diversity and phylogeographic structure of C. americana in eastern North America, microsatellite markers were developed and characterized for the first time in this species. Using these newly generated markers along with sequences from the plastid genome, the persistence of a minimum of two glacial refugia at the last glacial maximum were inferred, one in Florida and southern Alabama and another in the Appalachian Mountains near the southern tip of Blue Ridge Mountains. The diversity seen across the southern Appalachian Mountains supports the hypothesis that populations derived from the southern and northern refugia come together in this area.
3

Adaptivní změny rozšíření populací v odpovědi na klimatické změny / Adaptive population shifts in response to climate change

Horníková, Michaela January 2021 (has links)
Adaptive population shifts in response to climate change Ing. Michaela Horníková, Doctoral thesis Abstract Understanding of species' reactions to past climate and environmental changes is a hot topic in many fields of biology as it is relevant also for addressing species' future under the contemporary climate change. Using an emerging model species, the bank vole, I combine genomic phylogeographic data with information on known intraspecific functional variability and environmental niche modelling and aim to elucidate the particular role of intraspecific variation and ultimately selection in shaping the species' response to the climatic and environmental changes after the end of the last glaciation. Based on the mtDNA markers, bank voles exhibit a complex phylogeographic pattern suggesting population replacement events during the postglacial recolonization of Europe and thus possible involvement of selection in the process. An extensive dataset of more than 6000 SNPs was used to search for signs of population replacement in the bank vole genomic DNA and to investigate the species' postglacial recolonization history throughout its European distribution range. The genomic data revealed even more complex population history than previously detected with mtDNA markers, including not only admixture but also...

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