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  • Artikel  (4)
  • Behavior  (1)
  • Editorials  (1)
  • International Organizations, K33 - International Law  (1)
  • Lamiaceae  (1)
  • FLUID MECHANICS AND HEAT TRANSFER
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Oecologia 74 (1987), S. 347-351 
    ISSN: 1432-1939
    Schlagwort(e): Pontederia cordata ; Bombus ; Tristyly ; Pollination ; Behavior
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The foraging behavior of the pollinators of tristylous Pontederia cordata was studied to determine if differences in floral morphology would lead to preferential visitation of the floral morphs. Although nectar production is not different in the three floral morphs, differences in the production and size of pollen grains produced by the three anther levels results in the morphs offering variable amounts of resources to pollen-collecting insects. Bumblebees (Bombus spp.) and the solitary bee Melissodes apicata used P. cordata primarily as a nectar source and therefore did not seem to exhibit any morph preference. In contrast, honeybees visited flowers mainly for pollen and preferred to forage on long-level anthers of the short-and mid-styled morphs. An analysis of the composition of corbicular pollen loads indicated that, relative to the frequency of production in the population: 1) honeybees collected an excess of pollen from long-level anthers; 2) bumblebees collected the three types of pollen without any apparent preference; and 3) M. apicata preferentially collected pollen from the short-level anthers — presumably because their proboscides are modified by the presence of tiny hairs. The results suggest that P. cordata in Ontario is serviced by a diverse, unspecialized pollinator fauna which is not co-adapted to the tristylous floral polymorphism.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Plant systematics and evolution 223 (2000), S. 211-219 
    ISSN: 1615-6110
    Schlagwort(e): Heterostyly ; distyly ; zygomorphic flowers ; self-compatibility ; protandry ; geitonogamy ; Lamiaceae ; rare plant species
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Heterostyly rarely occurs in families with strongly zygomorphic flowers. For this reason Darwin (1877) doubted whether heterostyly would occur in the Lamiaceae and recent reviews have not reported the floral polymorphism in this family. Here we describe distyly in a rare species ofSalvia restricted to bluffs and seaward canyons on Santa Rosa Island (Santa Barbara Co., California) and northwestern Baja California (Mexico).Salvia brandegeei is morphologically distylous with populations composed of equal frequencies of long-and short-styled morphs differing reciprocally in stigma and anther position. Controlled hand pollinations demonstrated no significant differences in the seed set of self, intramorph or intermorph pollinations. Unlike most heterostylous species investigated,S. brandegeei does not possess diallelic incompatibility or ancillary polymorphisms of pollen and stigmas. We propose that the evolution of distyly inS. brandegeei may have been associated with an ecological shift to a new environment in which protandry failed to prevent increased levels of geitonogamy. Heterostyly was then selected because it increased the proficiency of cross-pollination. The origin of distyly in self-compatibleS. brandegeei is consistent with Lloyd and Webb's theoretical model for the evolution of distyly.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    facet.materialart.
    Unbekannt
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publikationsdatum: 2018-12-14
    Schlagwort(e): Editorials
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Geologie und Paläontologie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Publikationsdatum: 2014-07-23
    Beschreibung: Due to the failure of international efforts to limit atmospheric concentrations of greenhouse gases, consideration is now being given to solar geoengineering—a deliberate intervention to limit global warming without altering the atmospheric concentration of greenhouse gases. In contrast to emission cuts, geoengineering is expected to be cheap, quick to lower temperature, and feasible through the use of a single intervention. However, geoengineering is an imperfect substitute for emission reductions and will likely have undesirable side effects, only some of which can be anticipated before geoengineering is deployed. Most importantly, because geoengineering can be undertaken unilaterally, it creates issues of governance: Who gets to decide if, when, and how geoengineering should be attempted? This article provides an introduction to the key issues surrounding the governance of this unprecedented technology. ( JEL : Q54, F53, K33)
    Schlagwort(e): Q54 - Climate ; Natural Disasters ; Global Warming, F53 - International Agreements and Observance ; International Organizations, K33 - International Law
    Print ISSN: 1750-6816
    Digitale ISSN: 1750-6824
    Thema: Energietechnik , Politikwissenschaft , Wirtschaftswissenschaften
    Publiziert von Oxford University Press
    Standort Signatur Erwartet Verfügbarkeit
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