Search for dissertations about: "Gnetales"
Found 5 swedish dissertations containing the word Gnetales.
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1. The Gnetales: fossils and phylogenies
Abstract : The phylogeny of seed plants has been debated for more than a hundred years and is still not fully understood. Morphological analyses have consistently resulted in a phylogeny in which cycads are the earliest diverging seed plants, and Gnetales and angiosperms are sisters. Molecular data has, however, rarely supported this result. READ MORE
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2. Pollination in Ephedra (Gnetales)
Abstract : Pollination, i.e., the transport of male gametophytes to female gametophytes, can occur with biotic or abiotic vectors and is necessary for fertilization and completion of the lifecycle in all seed plants. READ MORE
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3. Evolutionary studies of the Gnetales
Abstract : The Gnetales consist of three distinct genera, Ephedra, Gnetum and Welwitschia with considerable divergence among them regarding morphological, ecological and molecular characters. A longstanding debate of the similarity between the Gnetales and angiosperms and the unresolved seed plant phylogeny intrigues plant scientists to further investigate the evolutionary history of the Gnetales. READ MORE
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4. Pollen and pollination in Ephedra (Gnetales)
Abstract : Ephedra (Gnetales) is a gymnosperm genus with a long evolutionary history; the first dispersed pollen grains with affinity to the group are known already from the Permian. This thesis focuses on the evolutionary history of the group and different aspects of its pollination mechanisms. READ MORE
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5. Proteomics and phylogenetics of the Gnetales
Abstract : A central point of Darwin’s theory of evolution is that accumulation of many small changes during the evolutionary process can result in significant change over time. In light of his theory, plant scientists seek for and compare different plant traits among species e.g. READ MORE