Visar resultat 1 - 5 av 6216 avhandlingar innehållade ordet Biologi.
Sammanfattning : Altitudinal gradients offer attractive opportunities for studies of population differentiation in response to environmental heterogeneity. In this thesis, I examined population differentiation along altitudinal gradients by combining common-garden experiments with field studies and experiments in alpine, subalpine and boreal populations of the perennial herb Solidago virgaurea. LÄS MER
Sammanfattning : Domestication greatly increases phenotypic variation in a short time span, with selection for a single phenotype and a plethora of associated phenotypic changes as an outcome of the process. The domestication process influences the underlying genomic architecture of a species, and the success and speed of the process is likely influenced by it. LÄS MER
3. Genomic and morphological diversity of marine planktonic diatom-diazotroph associations : a continuum of integration and diversification through geological time
Sammanfattning : Symbioses between eukaryotes and nitrogen (N2)-fixing cyanobacteria (or diazotrophs) are quite common in the plankton community. A few genera of diatoms (Bacillariophyceae) such as Rhizosolenia, Hemiaulus and Chaetoceros are well known to form symbioses with the heterocystous diazotrophic cyanobacteria Richelia intracellularis and Calothrix rhizosoleniae. LÄS MER
Sammanfattning : Reproduction in vertebrates, including fishes, is under control of the brain-pituitary-gonad (BPG) axis. The female three-spined stickleback, Gasterosteus aculeatus, produces egg clutches at intervals of a few days and spawns them in a nest built by male. LÄS MER
Sammanfattning : One of the most unforgiving processes in nature is that of Muller's ratchet, a seemingly irreversible accumulation of deleterious mutations that all organisms have to deal with or face extinction. The most obvious way to avoid fitness collapse is recombination, though asexual populations usually do not have the luxury of recombining freely. LÄS MER