Abstract
Plant reproductive success within a patch may depend on plant aggregation through pollinator attraction. For rewardless plants that lack rewards for pollinators, reproductive success may rely strongly on the learning abilities of pollinators. These abilities depend on relative co-flowering rewarding and rewardless plant species spatial distributions. We investigated the effect of aggregation on the reproductive success of a rewardless orchid by setting up 16 arrays in a factorial design with two levels of intraspecific aggregation for both a rewardless orchid and a rewarding co-flowering species. Our results show that increasing aggregation of both species negatively influenced the reproductive success of the rewardless plants. To our knowledge, this is the first experimental study demonstrating negative effects of aggregation on reproductive success of a rewardless species due both to its own spatial aggregation and that of a co-flowering rewarding species. We argue that pollinator learning behaviour is the key driver behind this result.
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Acknowledgements
This research was supported by the Swiss National Science Foundation research grant reference 3100A0-100754/1 to Luc D. B. Gigord, and the Roche Research Foundation Grant 22-2004 to Giorgina Bernasconi and Luc D. B. Gigord. Ann Smithson was funded by a British Ecological Society Special Ecological Project grant on the conservation of rewardless orchids. We are very grateful to Mailyn Gonzalez, Aline Pasche, Tiziana Ulian, Yves Delacrétaz, Javier Vences, Christine Gruffaz and the Baraille and Passet families for their inestimable support with the experiment. We also thank Giorgina Bernasconi, Guillaume Evanno and Pascal Vittoz for constructive comments on early versions of the manuscript.
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Communicated by Jacqui Shykoff.
The authors declare that the experiments presented here comply with the current laws applicable in the country in which they were performed (France).
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Internicola, A.I., Juillet, N., Smithson, A. et al. Experimental investigation of the effect of spatial aggregation on reproductive success in a rewardless orchid. Oecologia 150, 435–441 (2006). https://doi.org/10.1007/s00442-006-0530-0
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DOI: https://doi.org/10.1007/s00442-006-0530-0