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Research Assistant

Dr. Petra Wester

Building: 26.13
Floor/Room: U1.43
Phone +49 211 81-13413


  • Master (o. Bachelor) -Arbeit im Institut für Sinnesökologie
  • Thema: undefinedBestäubungsökologie in Südafrika

Research projects

Pollination by non-flying mammals
(co-operation with Prof. Dr. Steve Johnson, University of KwaZulu-Natal in Pietermaritzburg, and Prof. Dr. Anton Pauw, University of Stellenbosch, South Africa)
In South Africa one of the most spectacular cases of pollinator interactions occurs: pollination by mice and elephant-shrews. Pollination by those animals was shown by observations, proof of pollen around snouts and in faeces of live-trapped animals, choice experiments, analysing pollen transfer effectiveness and evaluating seed set after selective exclusion experiments. Plants adapted to these animals, e.g. Whiteheadia bifolia (Hyacinthaceae) or Hyobanche atropurpurea (Orobanchaceae), show characters like visually inconspicuous flowers near ground level with stiff stamens. Floral scent seems to play a major role as attractant, analysed with gas chromatography-mass spectrometry.
Currently, further plants and non-flying mammals are being investigated, especially floral scent and its attractiveness to pollinators. In future, similar relationships will be investigated in other countries.

Pollination ecology of the genus Salvia
(co-operation with Prof. Dr. Regine Claßen-Bockhoff, Institut für Spezielle Botanik und Botanischer Garten, Johannes Gutenberg-University Mainz, Germany)
The genus Salvia includes more than 900 species and is characterised by lever-like stamens playing a central role in the process of pollen transfer. Different aspects of pollination ecology are studied, such as the role of different pollinators in driving speciation and morphological adaptations to different pollinator groups.

The role of pollinators in hybridisation at the example of South African Salvia species

(co-operation with Prof. Dr. Anton Pauw and Dr. Jaco Le Roux, University of Stellenbosch, South Africa)
In the Western Cape of South Africa hybrid swarms of three different Salvia species occur between one bee-pollinated and two bird-pollinated parents. Birds and pollen-collecting bees (mainly honeybees) contribute to the breakdown of reproductive isolation. We are currently busy with testing whether the floral diversity is mirrored by genetic diversity.

Mechanical exclusion of flower visitors
(co-operation with Prof. Dr. Klaus Lunau, Heinrich-Heine-University of Düsseldorf, Germany)
Flowers specialized on certain pollinators often filter out visitors that are not suitable for efficient pollination. Floral filters might be floral colour, scent or morphology such as size of floral entrance and length of floral tube. In addition movable parts in flowers are known to prevent visitors from entering the flower. The diversity of this biomechanical floral filter is being investigated, including floral architecture and forces necessary to move the floral parts. Additionally visitor behaviour and forces exerted by insects to gain access to a food source (nectar, pollen) will be studied.

Pollinator effectiveness
(co-operation with Prof. Dr. Steve Johnson, University of KwaZulu-Natal in Pietermaritzburg, South Africa)
Flowers that are visited by a broad assemblage of animals may nevertheless be considered relatively specialised if pollination is effected mainly by a subset of these visitors. The importance of a particular group of animals for pollination of a plant species derives mainly from the relative rate of floral visitation and per-visit effectiveness of the animals for pollen deposition. We assessed the relative importance of different animals for pollination of South African plants.

Foraging behaviour of nectarivorous birds
A long-standing dogma in pollination biology was that New World hummingbirds hover and Old World birds perch when visiting flowers for nectar. Case studies of South African birds and an overview of hovering behaviour and its frequency in nectarivorous Old World birds show that hovering behaviour is more common than expected in the Old World. The foraging behaviour of specialist nectarivorous passerines is more similar to that of hummingbirds than to that of generalist passerines.


  • Since 2013 Research Assistant, Institute of Sensory Ecology, Heinrich-Heine-University of Düsseldorf, Germany
  • 2010-2013 Post-doctoral researcher, School of Life Sciences, University of KwaZulu-Natal, Pietermaritzburg, South Africa
  • 2007-2010 Post-doctoral researcher, Department of Botany and Zoology, University of Stellenbosch, South Africa (Research fellowship of the Claude Leon foundation, Cape Town)
  • 2001-2007 Research associate, Institut für Spezielle Botanik und Botanischer Garten, Johannes Gutenberg-University Mainz, Germany; PhD: Ornithophily in the genus Salvia
  • 2000-2001 Research associate, Department of Ecology, University of Osnabrück, Germany, BMBF (Federal ministry of education and research)-project ‚Inland sand ecosystems – dynamics and restitution’
  • 1999 Diploma (Biology), Thesis: ‘Chemotypes of wild-thyme (Thymus pulegioides L., Lamiaceae) and their relations to spatially associated plants in a limestone grass-land (Hämmersberg/Northern Eifel/Western Germany)’; Institute of Agronomic Botany, Department of Geobotany and Nature Conservation, Rheinische Friedrich-Wilhelms-University, Bonn, Germany
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