Comparative biology of pollination systems in the African-Malagasy genus Brownleea (Brownleeinae: Orchidaceae) |
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Authors: | MICHAEL W LARSEN CRAIG PETER STEVEN D JOHNSON JENS M OLESEN |
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Institution: | Department of Biological Sciences, Section of Ecology and Genetics, University of Aarhus, Ny Munkegade 1540, 8000, Denmark; Department of Botany, Rhodes University, PO Box 94, Grahamstown, 6140, South Africa; School of Biological and Conservation Sciences, University of KwaZulu-Natal, P. Bag X01, Scottsville, Pietermaritzburg 3209, South Africa |
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Abstract: | The role of pollinators in the evolution of the African-Malagasy orchid genus Brownleea (Brownleeinae) was investigated. Taxa show specialization for pollination by bees ( B. parviflora , B. recurvata ), short-proboscid flies ( B. galpinii ), and long-proboscid flies ( B. macroceras , B. coerulea ). All species in the genus produce nectar, but some ( B. coerulea , B. galpinii ) appear to mimic flowers of abundant sympatric species as an additional strategy to attract pollinators. Species investigated in terms of their breeding systems ( B. coerulea , B. parviflora , B. macroceras , B. galpinii ) are reliant on pollinator visits for seed production. Self-pollination results in strong inbreeding depression during embryo formation. A phylogeny of the genus, constructed using data from the ITS1-5.8S-ITS2 region and morphology, indicates that fly pollination is likely to be basal in the genus, and that there has been a single shift to bee pollination. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society , 2008, 156 , 65–78. |
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Keywords: | adaptive radiation biogeography floral syndrome internal transcribed spacer (ITS) Madagascar nectar pollinia South Africa |
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