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Visar resultat 1 - 5 av 102 avhandlingar som matchar ovanstående sökkriterier.
1. Evolution and biodiversity of the Ixoroideae (Rubiaceae)
Sammanfattning : The phylogenetic relationships within subfamily Ixoroideae of the coffee family are investigated by phylogenetic reconstruction of molecular data, including regions of the chloroplast DNA (matK, ndhF, rbcL, rps16, trnH-psbA, trnS-G, and trnT-F), and the nuclear ribosomal DNA (ITS). The evolution of morphological characters within the group are inferred, with focus on characters used in classification. LÄS MER
2. Comparative morphological studies of fossil and living plane trees (Platanaceae) and oaks (Quercus): taxonomy, ecology, evolution
Sammanfattning : Morphological characters are essential for flowering plant identification, but also provide information about diversity patterns and ecological adaptation. In woody plant species, characters of the leaf are among the most useful and can be examined on fossils as well. LÄS MER
3. Ecology and Evolution of Resistance to Herbivory : Trichome Production in Arabidopsis lyrata
Sammanfattning : In this thesis, I examine variation in occurrence and performance of glabrous and trichome-producing plants of the perennial herb Arabidopsis lyrata. I combine field studies and genetic analysis to (1) examine the function of trichomes as a resistance character in natural populations, (2) compare the magnitude of population differentiation in trichome-production and at putatively neutral marker loci, (3) examine the molecular genetic basis of trichome-production, and (4) quantify the effects of herbivore removal on population growth and relative performance of glabrous and trichome-producing plants. LÄS MER
4. Selection and Floral Evolution in Platanthera bifolia and P. chlorantha (Orchidaceae)
Sammanfattning : Natural selection mediated by pollinators has influenced the evolution of floral diversity of the flowering plants (angiosperms). The scope of this thesis was to study: 1) phenotypic selection, 2) mating systems, and 3) floral shifts involved in plant speciation. Model plant species were Platanthera bifolia and P. chlorantha (Orchidaceae). LÄS MER
5. Patterns of evolution in a young species, the Baltic seaweed Fucus radicans
Sammanfattning : To be able to interpret patterns of biodiversity it is important to understand the processes by which new species evolve and how closely related species remain reproductively isolated and ecologically differentiated. This thesis centers on the evolution of the two brown algae Fucus radicans and Fucus vesiculosus in the Baltic Sea, where Fucus radicans very recently diverged from F. LÄS MER