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Visitor profiles for related sympatric Cape plants

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Nelson, Leanne 2010 , 'Visitor profiles for related sympatric Cape plants', Coursework Master thesis, University of Tasmania.

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Abstract

Many angiosperms require the pollination services of insects to effectively transfer
pollen between conspecifics. Closely-related plants that overlap in their range and utilise
the same pollinators may experience interspecific pollen flow which can lead to a
reproductive disadvantage and increase the likelihood of hybridisation. Reproductive
isolation among plants is achieved either by the structural mechanisms of flowers that
preclude entry to or pollination by certain species, or the foraging behaviour of the
pollinator fauna when they restrict their visits to one particular species. The fynbos flora
in the southwestern Cape of South Africa is characterised by extremely high species
diversity among various genera, but the pollination ecology of most of the flora remains
poorly known. This flora offers a remarkable opportunity to explore details of the insect
flower interaction in communities ofrelated plants. The main objective of this study was
to examine the extent of overlap and pollinator sharing in a sample of this assemblage by
comparing the diversity and abundance of floral visitors among several related species
pairs. Field studies were conducted over summer on the visitor profiles of three pairs of
closely-related, sympatric plant species (Erica daphniflora/E. multumbellifera; Lobelia
tomentosa/L. erinus; Lobelia neglecta colour polymorphs) at Wildcliff Nature Reserve.
Levels of interspecific pollen flow and flower constancy were assessed by observing the
sequential movements of all visitors, and their body and wing dimensions were
measured to analyse variation in the morphological profile of visitors associated with
each plant species and between telated pairs. A range of taxonomically diverse insects
(29 species from four orders) were identified as flower visitors - Hymenoptera (primarily
apid bees), Diptera, Coleoptera and Lepidoptera and all plants maintained generalist
pollination systems. Ordination methods reveal nominal overlap in the visitor profiles for
each plant pair and high levels of flower constancy were observed among all insect taxa.
A principal components analysis identified wing width as varying independently of other
size variables and this is thought to have an influence on pollinator behaviour through its
influence on flight control. I discuss these findings in the context of pollinator behaviour,
insect and plant morphology and community composition.

Item Type: Thesis - Coursework Master
Authors/Creators:Nelson, Leanne
Keywords: Fynbos ecology, Angiosperms, Insect-plant relationships
Copyright Holders: The Author
Copyright Information:

Copyright 2010 the author - The University is continuing to endeavour to trace the copyright
owner(s) and in the meantime this item has been reproduced here in good faith. We
would be pleased to hear from the copyright owner(s).

Additional Information:

Available for use in the Library and copying in accordance with the Copyright Act 1968, as amended. Thesis (MAppSc)--University of Tasmania, 2011. Includes bibliographical references

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