Connective appendages in Huberia bradeana (Melastomataceae) affect pollen release during buzz pollination

T. Bochorny, L.F. Bacci, A.S. Dellinger, F.A. Michelangeli, R. Goldenberg, V.L.G. Brito

Abstract Floral structures such as stamen appendages play crucial roles in pollinator attraction, pollinator positioning, pollen-release dynamics and, ultimately, the reproductive success of plants. The pollen-rewarding, bee-buzz-pollinated flowers of Melastomataceae often bear conspicuous staminal appendages. Surprisingly, their functional role in the pollination process remains largely unclear. We use Huberia bradeana Bochorny & R. Goldenb. (Melastomataceae) with conspicuously elongated, twisted stamen appendages to investigate their functional role in the pollination process. We studied the effect of stamen appendages on pollinator behavior and reproductive success by comparing manipulated flowers (appendages removed) with unmanipulated flowers. To assess bee-pollinator behavior, we measured three properties of buzzes (vibrations) produced by bees on Huberia flowers: frequency, duration and the number of buzzes per flower visit. We measured male and female reproductive success by monitoring pollen release and deposition after single bee visits. Finally, we used artificial vibrations and laser vibrometry to assess how flower vibrational properties change with the removal of stamen appendages. Our results show that the absence of staminal appendages does not modify bee buzzing behavior. Pollen release was higher in unmanipulated flowers but stigmatic pollen loads differ only marginally between the two treatments. We also detect lower vibration amplitudes in intact flowers as compared to manipulated flowers in artificial vibration experiments. These results suggest that stamen appendages are crucial in transmitting vibrations and assuring optimal pollen release in buzz-pollinated flowers.

Department für Botanik und Biodiversitätsforschung
Externe Organisation(en)
Universidade Estadual de Campinas, New York Bot Garden, Federal University of Parana, Universidade Federal de Uberlândia, Instituto de Biologia, Uberlândia, Minas Gerais, Brazil
Plant Biology
ÖFOS 2012
106008 Botanik, 106042 Systematische Botanik, 106012 Evolutionsforschung
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