Search for dissertations about: "non-random selection"

Showing result 1 - 5 of 13 swedish dissertations containing the words non-random selection.

  2. 1. Pollen Competition as a Target for Sexual Selection in Plants

    Author : Åsa Lankinen; Biologiska institutionen; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Sexual selection; Pollen tube growth rate; Pollen selection models; Pollen interactions; Pollen competition; Plants; Phenotypic plasticity; Non-random mating; Genotype by environment interactions; Mate choice; Viola tricolor.; Plant ecology; Växtekologi;

    Abstract : According to the theory of sexual selection, traits can evolve because they confer a mating advantage in competition with members from the same sex. In animals, sexual selection is considered as an important evolutionary force. In this thesis I have investigated the potential for sexual selection in plants. READ MORE

  4. 2. Male and female selective mechanisms, reproductive success and gene flow

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

    Abstract : 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. READ MORE

  5. 3. Measuring long-term effects of a school improvement initiative

    Author : Joakim Svärdh; Inga-Britt Skogh; Erik Mellander; Veronica Bjurulf; Monica Rosén; KTH; []
    Keywords : SAMHÄLLSVETENSKAP; SOCIAL SCIENCES; Propensity Score Analysis PSA ; effect study; quantitative evaluation; educational intervention; compulsory school; Science and Technology for All Initiative; representative sample; non-random selection; multi-level modelling; post-matching multivariate regression;

    Abstract : There is a growing demand for studies applying quantitative methods to large-scale data sets for the purpose of evaluating the effects of educational reforms (UVK, 2010). In this thesis the statistical method, Propensity Score Analysis (PSA), is presented and explored in the evaluating context of an extensive educational initiative within science and technology education; the Science and Technology for All-program (NTA). READ MORE

  6. 4. Reproductive Biology and Population Genetics of Common Ash (Fraxinus excelsior L.)

    Author : Grazyna Bochenek; Göteborgs universitet; []
    Keywords : Fraxinus excelsior; delayed fertilization; functional dioecy; gender-related grow difference; inbreeding; tree-rings; non random mating; wind-pollination;

    Abstract : Common Ash, Fraxinus excelsior L. (Oleaceae) is a wind-pollinated, wind-dispersed, deciduous tree, commonly occurring throughout Central and Northern Europe. The thesis addresses several questions concerning reproductive biology and factors influencing the genetic richness of ash stands. READ MORE

  7. 5. Genome Variation in Human Populations : Exploring the Effects of Demographic History and the Potential for Mapping of Complex Traits

    Author : Åsa Johansson; Ulf Gyllensten; Marta Alarcon; Andrew Clark; Uppsala universitet; []
    Keywords : Genetics; genetics; evolution; microsatellie; SNP; selection; linkage disequilibrium; haplotype; Genetik;

    Abstract : A major challenge in human genetics is to understand the genetic variation underlying common diseases. In this thesis, I focus on forces creating differences between individuals and genomic regions, methods for characterizing genomic variation, and the association between genomic and phenotypic variation. READ MORE