Sökning: "spur length"

Visar resultat 1 - 5 av 8 avhandlingar innehållade orden spur length.

  1. 1. Evolution of Spur Length in a Moth-pollinated Orchid

    Författare :Elin Boberg; Jon Ågren; W. Scott Armbruster; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Platanthera bifolia; floral evolution; natural selection; pollination; spur length; population differentiation; divergent selection; disruptive selection; reproductive isolation; Biology; Biologi; Ecological Botany; Ekologisk botanik;

    Sammanfattning : There is considerable evidence that pollinator shifts can explain many differences in flower morphology between closely related plant species, but the extent to which pollinator shifts can explain the maintenance of among-population variation in floral traits within species is poorly known. In this thesis, I combined comparative and experimental approaches to examine the evolution of floral traits in the moth-pollinated orchid Platanthera bifolia. LÄS MER

  3. 2. Pollinator-mediated selection and the evolution of floral traits in orchids

    Författare :Judith Trunschke; Jon Ågren; Nina Sletvold; Allan G. Ellis; Uppsala universitet; []
    Nyckelord :Among-population variation; Ecotype; Field experiment; Floral evolution; Germination; Local adaptation; Orchidaceae; Platanthera bifolia; Phenotypic selection; Pollination; Reciprocal transplant; Trait manipulation; Biology with specialization in Ecological Botany; Biologi med inriktning mot ekologisk botanik;

    Sammanfattning : In this thesis, I combined manipulations of traits and pollination environment with analysis of phenotypic selection to examine causes of variation in strength and mode of selection on floral traits, and I conducted a reciprocal sowing experiment to test for local adaptation in germination success. I tested the following predictions (1) the opportunity for selection, and the strength of pollinator-mediated and net selection increase with increasing pollen limitation, (2) the effects of traits affecting pollinator attraction and traits affecting pollination efficiency are non-additive and this leads to pollinator-mediated correlational selection, (3) the effects of spur length on pollen removal, pollen receipt, and female fitness differ between populations with short-tongued and populations with long-tongued pollinators, and (4) local adaptation at the stage of germination contributes to the maintenance of ecotypes growing in grasslands and woodlands, respectively. LÄS MER

  4. 3. The Impact of the Patent System on Innovation

    Författare :Julian Boulanger; Handelshögskolan i Stockholm; []
    Nyckelord :SAMHÄLLSVETENSKAP; SOCIAL SCIENCES;

    Sammanfattning : This Ph.D. thesis contains the following three independent chapters."Patents and Follow-On Innovation: Evidence From Patent Renewal Decisions" examines whether patent protection on existing technologies blocks or facilitates technical advances that spur from those existing technologies. LÄS MER

  5. 4. Evolutionary Ecology of Floral Traits in Fragrant Orchids

    Författare :Elodie Chapurlat; Nina Sletvold; Jon Ågren; Magne Friberg; Kathleen Kay; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; agents of selection; diurnal and nocturnal pollination; divergent selection; field experiment; floral evolution; floral scent; Gymnadenia conopsea; Gymnadenia densiflora; Orchidaceae; phenotypic selection; pollinator-mediated selection; spatial variation; scent rhythm;

    Sammanfattning : Why are flowers so diverse? Much of floral evolution is thought to be driven by pollinator-mediated selection. However, the connection between macroevolutionary patterns of floral diversity and microevolutionary processes remains poorly understood. In this thesis, I have used the fragrant orchids Gymnadenia conopsea s.s. LÄS MER

  7. 5. Development and maintenance of quality indicators in pheasants

    Författare :Thomas Ohlsson; Biologiska institutionen; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; PHA; ELISA; immunocompetence; carotenoid coloration; male ornaments; fluctuating asymmetry; growth; early development; Phasianus colchicus; egg size; sexual selection; Animal ecology; Djurekologi; Ecology; Ekologi;

    Sammanfattning : Females often base their choice of mates on the expression, size or intensity, of male sexual ornaments. Indicator models of sexual selection assume that females assess male genetic quality through the expression of these secondary sexual characters. LÄS MER