Oecologia

, Volume 147, Issue 1, pp 60–68 | Cite as

Lack of floral nectar reduces self-pollination in a fly-pollinated orchid

Plant Animal Interaction

Abstract

One explanation for the widespread absence of floral nectar in many orchids is that it causes pollinators to visit fewer flowers on a plant, and thus reduces self-pollination. This, in turn, could increase fitness by reducing inbreeding depression in progeny and promoting pollen export. The few previous investigations of this hypothesis have all involved bee-pollinated orchids and some have given contradictory results. We studied the effects of adding artificial nectar (sucrose solution) to the spurs of a non-rewarding long-proboscid fly-pollinated orchid, Disa pulchra. Addition of nectar significantly increased the number of flowers probed by flies (2.6-fold), the time spent on a flower (5.4-fold), the number of pollinia removed per inflorescence (4.8-fold) and the proportion of removed pollen involved in self-pollination (3.5-fold). The level of self-pollination increased dramatically with the number of flowers probed by flies. Experimental self-pollination resulted in fruits with only half as many viable seeds as those arising from cross-pollination. Pollinators were more likely to fly long distances (>40 cm) when departing from non-rewarding inflorescences than when departing from rewarding ones. These findings provide support for the idea that floral deception serves to reduce pollinator-mediated self-pollination.

Keywords

Disa pulchra Inbreeding depression Geitonogamy Plant–pollinator interaction Pollen dispersal 

Notes

Acknowledgements

We would like to thank L. Harder, B. Anderson and two anonymous reviewers for their very helpful comments on the manuscript. We are grateful to I. Schodelbauerová for the help with seeds viability analyses. This work was supported by a grant from the Academy of Sciences of the Czech Republic No. KJB6141302 and postdoctoral funding from the South African National Research Foundation to J. Jersáková.

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Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  1. 1.School of Biological and Conservation SciencesUniversity of KwaZulu NatalPietermaritzburgSouth Africa
  2. 2.Faculty of Biological SciencesUniversity of South BohemiaČeské BudějoviceCzech Republic
  3. 3.Department of Theoretical EcologyInstitute of System Biology and Ecology AS CRČeské BudějoviceCzech Republic

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