Sökning: "pollinators"
Visar resultat 21 - 25 av 45 avhandlingar innehållade ordet pollinators.
21. The Ecology of Floral Signals in Penstemon digitalis
Sammanfattning : In this thesis, I combined field observations and lab experiments to explore the ecological significance of floral signals in a North American wildflower, Penstemon digitalis. More specifically, to determine the potential mechanisms driving selection on floral scent, I studied how scent mediates interactions with pollinators and antagonists by (1) observing spatiotemporal variation in scent emission (2), floral volatile ability to suppress microbes (3) the honest advertisement of nectar, and (4) if scent could aid pollinator learning by reinforcing visual signals. LÄS MER
22. Pollinator-mediated selection and the evolution of floral traits in orchids
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
23. Plant-animal interactions and seed output of two insectpollinated herbs
Sammanfattning : I combined comparative and experimental studies in the field and in the greenhouse to examine factors influencing reproductive success in two insect-pollinated herbs, the tristylous, selfincompatible perennial Lythrum salicaria and the self-compatible, biennial Pedicularis palustris. More specifically, I explored (i) the effects of plant population characteristics on the intensity and outcome of interactions with pollinators and seed predators, (ii) whether flower morphology affects duration of stigma receptivity, and (iii) whether damage-induced reduction in floral display reduces pollinator visitation and increases pollen limitation. LÄS MER
24. Flower Cues for Hawkmoths: Colour, Place and Odour
Sammanfattning : Flowers use different cues to attract pollinators including colour and odour. How do hawkmoths use these cues to find the flowers? This question was investigated in two species of hawkmoth, the diurnal species, Macroglossum stellatarum, and the nocturnal species, Deilephila elpenor. Both species have colour vision and D. LÄS MER
25. Local and landscape-level impacts of agricultural intensification on arthropod communities and their interaction networks
Sammanfattning : Arthropods play a central role in agricultural landscapes being responsible for the delivery of many ecosystem services such as pollination, biological pest control, and nutrient cycling. But the current global decline of arthropods is intensified by habitat modification, loss and fragmentation, pesticide use and other intensive management practices. LÄS MER