Ecology and Pollination of Deceptive New Zealand Greenhood and Spider Orchids

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dc.contributor.advisor Gaskett, A en
dc.contributor.advisor Beggs, J en Bodley, Emma en 2014-05-04T20:39:33Z en 2013 en
dc.identifier.uri en
dc.description Full text is available to authenticated members of The University of Auckland only. en
dc.description.abstract Orchidaceae is a highly diverse family of plants that have various unusual pollination systems often involving deceit of pollinators and specific pollinator-plant interactions. Our knowledge of New Zealand orchid pollination ecology is relatively limited and there are a large number of orchids that have not been formally characterised. Diplodium brumale is a winter flowering greenhood orchid that is thought to deceive male fungus gnats (Mycetophilidae). Nematoceras are spider orchids thought to attract female fungus gnats by brood-site deception. Here I aimed to understand the pollination systems of both greenhood and spider orchids. I documented the phenology, pollination limitations and pollination success of D. brumale. Orchid height was measured and stages of development were recorded during the flowering season. Pollinator exclusion bags were set up with four hand pollination treatments applied to test pollen limitation. D. brumale showed very low fruit (1-12%) and seed (1-4%) set. D. brumale requires insect mediated, cross pollination for successful reproductive output, despite its self-compatibility. I also investigated visual pollinator attraction of D. brumale. Spectral sensitivities of D. brumale were measured and modelled into the fly-specific categorical vision model and receptor noise limited colour opponent model. The fly-specific categorical vision model showed that flies cannot differentiate between the orchid and its background, and D. brumale probably uses colour as a camouflage mechanism against herbivory. The second model suggested flies could differentiate between orchid colours and their backgrounds which suggest that intensity of light may play a role in pollinator identification of flowers. I also attempted to identify the pollinator of D. brumale by trapping insects over the flowering season. The possible pollinator of this orchid was suggested Mycetophila species and no pollinator behaviour was observed. Pollinia was found on one female Mycetophila vulgaris. I investigated olfactory and tactile pollinator cues in three Nematoceras species, seven Nematoceras forms and D. brumale using scanning electron microscopy (SEM). Both Nematoceras and D. brumale lacked evidence of scent glands on the lateral sepals and hairs dominated labella surfaces. There was a lack of evidence for olfactory and tactile pollinator attractants. It is still unclear what pollinator attractant methods these orchids employ. D. brumale will be highly sensitive to changes in pollinator abundances due to the low reproductive output and dependency on a vector for pollination. Data in this thesis has provided insight into the ecology and pollination systems of New Zealand orchids, and has contributed to the broader theory on the evolution of deceptive plant-insect interactions. en
dc.publisher ResearchSpace@Auckland en
dc.relation.ispartof Masters Thesis - University of Auckland en
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher. en
dc.rights Restricted Item. Available to authenticated members of The University of Auckland. en
dc.rights.uri en
dc.title Ecology and Pollination of Deceptive New Zealand Greenhood and Spider Orchids en
dc.type Thesis en The University of Auckland en Masters en
dc.rights.holder Copyright: The Author en
pubs.elements-id 437536 en
pubs.record-created-at-source-date 2014-05-05 en

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