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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Plant systematics and evolution 207 (1997), S. 273-283 
    ISSN: 1615-6110
    Schlagwort(e): Nymphaeaceae ; Nuphar lutea ; N. pumila ; Donacia ; Hydrellia ; Notophila ; Scatophagidae ; Ephydridae ; Pollination ; sympatry ; allopatry ; self-compatibility
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Nuphar (Nymphaeaceae) comprises a small holarctic group of aquatic perennials whose flowers are pollinated by flies, bees, and beetles. We studied pollination in different populations of the two European speciesN. lutea andN. pumila in Norway and in Germany. Flowers are self-compatible and protogynous, preventing automatic selfing, and insect pollination is required for seed production. Sympatric populations were studied in Vest-Agder county in Norway to determine whetherN. lutea andN. pumila have the same or different pollinators. Allopatric populations ofN. lutea in Germany and Norway were then compared to determine whether their pollinator spectra differ as would be expected in an open flower with seemingly easily accessible pollen and nectar. Results of the present as well as previous studies of the pollination ofN. lutea andN. pumila show that both species are mainly pollinated by flies, including apparentNuphar specialists, such as the scatophagidHydromyza livens and the ephydridsHydrellia andNotiphila, the last also a long-known pollinator ofN. advena in Florida. Pollinator overlap between sympatric heterospecific populations was small, while allopatric conspecific populations had similar visitor and pollinator spectra. We found no evidence of pollination byDonacia beetles as reported from some North American populations ofNuphar.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    Publikationsdatum: 2014-11-11
    Beschreibung: Flexibility can be considered a crucial factor of competitive advantage, especially under conditions of dynamically changing environments. Based on the classical microeconomic definition, flexibility is characterised as a firm's ability to change output by sustaining its average costs. Using some recent concepts developed in production economics, this article proposes a primal flexibility measure for multi-product firms. When decomposed, this measure offers useful insights into possible sources of flexibility, especially by investigating the role of both scale and scope economies. This approach provides the theoretical basis for our investigation into the magnitude and sources of flexibility in the Polish agricultural sector.
    Schlagwort(e): D24 - Production ; Cost ; Capital and Total Factor Productivity ; Capacity, I25 - Education and Economic Development, Q12 - Micro Analysis of Farm Firms, Farm Households, and Farm Input Markets
    Print ISSN: 0165-1587
    Digitale ISSN: 1464-3618
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Wirtschaftswissenschaften
    Publiziert von Oxford University Press
    Standort Signatur Einschränkungen Verfügbarkeit
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