Sökning: "frequency-dependent selection"

Visar resultat 1 - 5 av 16 avhandlingar innehållade orden frequency-dependent selection.

  1. 1. Pollinators, Enemies, Drought, and the Evolution of Reproductive Traits in Primula farinosa

    Författare :Per Toräng; Jon Ågren; Johan Ehrlén; Rebecca Irwin; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Ecology; Alternative reproductive strategies; climate change; facilitation; floral display; flowering phenology; frequency-dependent selection; genetic diversity; life-history strategies; local adaptation; pollination; predation; Primula farinosa; reproductive effort; soil disturbance; stochastic growth rate; Ekologi;

    Sammanfattning : In this thesis, I combined comparative and experimental approaches to examine selection on reproductive traits and population differentiation in the insect-pollinated, self-incompatible, perennial herb Primula farinosa. More specifically, I (1) determined whether the effects of floral display and interactions with pollinators and seed predators, and plant reproductive success were frequency-dependent and affected by surrounding vegetation context, (2) examined the consequences of intermittent drought years on population dynamics using numerical simulations based on demographic data collected over seven years, (3) analyzed among-population differentiation in flowering phenology and reproductive allocation, and its relationship to soil-depth at the site of origin. 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. 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

  5. 4. Sexual Selection and Adaptation to Novel Environments

    Författare :Ivain Martinossi-Allibert; David Berger; Göran Arnqvist; Lukas Schärer; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Sexual selection; Environmental change; Sexual conflict; Environmental stress; Adaptation; Adaptive landscape; Biologi med inriktning mot zooekologi; Biology with specialization in Animal Ecology;

    Sammanfattning : The work included in this thesis aims at exploring the environmental sensitivity of benefits and costs of sexual selection through a combined empirical and theoretical effort, to increase our understanding of the impact of environmental change on sexually reproducing populations.Can sexual selection promote adaptation to novel environments? Sexual selection for good genes should accelerate adaptation by granting higher reproductive success to individuals of high genetic quality. LÄS MER

  7. 5. 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