Sökning: "natural selection"

Visar resultat 11 - 15 av 1235 avhandlingar innehållade orden natural selection.

1. 11. Quo vadis? Insights into the determinants of evolutionary dynamics

   Författare :Alexandre Rêgo; Rike Stelkens; Dmitri Petrov; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; natural selection; selection; genetic drift; evolutionary rescue; historical contingency; adaptation; complex environments; evolutionary predictability; parallel evolution; populationsgenetik; Population Genetics;

   Sammanfattning : Predicting future evolutionary outcomes and explaining past and current patterns of biodiversity are fundamental goals in evolutionary biology. Trajectories of evolving populations are determined by evolutionary mechanisms (natural selection, mutation, genetic drift, and gene flow) and the environment in which the populations are found. LÄS MER

3. 12. Male and female selective mechanisms, reproductive success and gene flow

   Författare :Samuel Kiboi; Biologiska institutionen; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Växtekologi; Plant ecology; Cucumis sativus.; genetic marker; gene flow; reproduction; embryo abortion; resistance; maternal selection; sexual selection; pollen competition; selection;

   Sammanfattning : In this thesis, I have studied male and female selective mechanisms that can affect plant reproductive success and gene flow. I have focussed on sexually selected traits, mainly pollen competition and maternal sorting mechanisms, for example through non-random ovule abortion. LÄS MER

4. 13. Pathogen-mediated selection in the immune system of rodents : Exploring selection targets, functional effects and trade-offs

   Författare :Mridula Nandakumar; Funktionell zoologi; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; pathogen-mediated selection; bank voles; Myodes glareolus; immune system; balancing selection; immune response; rodents; positive selection; transcriptomics;

   Sammanfattning : Pathogens cause disease and play an important role in shaping evolution of the host immune system. They create pressure on host immunity to evolve in numerous ways, most commonly by increasing divergence between species (positive selection) or increasing polymorphisms within a population (balancing selection). LÄS MER

5. 14. Metals in Dynamic Chemistry: Selection & Catalysis

   Författare :Brian J.J. Timmer; Olof Ramström; Stéphane Bellemin-Laponnaz; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; constitutional dynamic chemistry; selection; multivalent interactions; carbohydrates; quartz crystal microbalance; catalyst screening; aqueous olefin metathesis; C-H activation; Kemi; Chemistry;

   Sammanfattning : In the adaptation to the oxidative environment on earth, metals played a crucial role for the evolution of life. The presence of metals also allowed access to advanced functions due to their unique coordination sphere and reactivity. LÄS MER

7. 15. Haploid selection in animals : Exploring the fitness consequences and underlying mechanisms

   Författare :Ghazal Alavioon; Simone Immler; Tommaso Pizzari; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; sperm; evolution; haploid selection; reproductive aging; fitness;

   Sammanfattning : A consequence of sexual reproduction in eukaryotes is the evolution of a biphasic life cycle with alternating diploid and haploid gametic phases. While our focus in evolutionary biology is on selection during the diploid phase, we know relatively little about selection occurring during the haploid gametic stage. LÄS MER