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Visar resultat 1 - 5 av 8 avhandlingar som matchar ovanstående sökkriterier.

  1. 1. MHC polymorphism and host-pathogen interactions: The case of Borrelia in its reservoir host, the bank vole Myodes glareolus

    Författare :Kristin Scherman; MEMEG; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Host-pathogen interaction; Negative frequency dependent selection; Myodes glareolus; Borrelia;

    Sammanfattning : The major histocompatibility complex (MHC) class IIB genes exhibit extensive allelic polymorphism, most likely maintained by pathogen-mediated balancing selection (PMBS). PMBS may operate in the form of heterozygote advantage (HA), and/or through the interaction of pathogens and specific MHC alleles via fluctuating selection (FS) or negative frequency-dependent selection (NFDS). LÄS MER

  3. 2. Mating system evolution and self-incompatibility in the wild plant species Brassica cretica

    Författare :Kristina Aaltonen; Biologiska institutionen; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; mating system; Brassicaceae; Brassica cretica; recombination; frequency-dependent selection; evolution; population structure; segregation distortion; SCR; self-incompatibility; SRK;

    Sammanfattning : Compared to animals like ourselves, plants have a very flexible sexual life. Most plants are, for example, hermaphrodites with the potential capacity for reproduction by self-fertilization (or selfing). LÄS MER

  4. 3. Ontogeny and Population Biology of a Sex-Limited Colour Polymorphism

    Författare :Jessica Abbott; Biologiska institutionen; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; embryologi; ontogeni; animal morphology; embryology; Utvecklingsbiologi; Damselflies; Colour polymorphism; Development; Frequency-dependence; Morphology; growth animal ; ontogeny; Animal anatomy; Development biology; Djurs anatomi och morfologi; Population divergence; Animal ecology; Djurekologi;

    Sammanfattning : This study has involved investigation of number of populations of the damselfly Ischnura elegans over several years, looking at frequency changes over time, morphological differences between the sexes and the morphs, differences in growth rate and development time, differences in fecundity between the morphs, and genetic differentiation between populations. I. LÄS MER

  5. 4. Adaptive evolution in multidimensional trait spaces

    Författare :Paula Vasconcelos; Claus Rüffler; Maria Servedio; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; adaptive dynamics; mutidimensional trait spaces; evolutionary dynamics; disruptive selection; resource competition; diversification;

    Sammanfattning : Negative frequency-dependent disruptive selection, which arises due to the interplay between organisms of a population and their environment, is an important element driving phenotypic diversification and even speciation. Such selection regime can result from frequency- and density-dependent interactions between the organisms and their environment, so that the fitness landscape itself changes as the population evolves. LÄS MER

  7. 5. The MHC genes: variation and impact on life-history traits in house sparrwos

    Författare :Maria Karlsson; MEMEG; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; MHC-I; house sparrow; 454-amplicon sequencing; cDNA; functional clustering; trans-species evolution; nestling survival; mate-choice;

    Sammanfattning : In birds the major histocompatibility complex (MHC) organization differs both among and within orders. Galliformes often have simple arrangements with few transcribed MHC genes whilst many songbirds (Passeriformes) have a complex arrangement with many MHC genes and also presence of pseudo-genes. LÄS MER