Abstract
The degree of specialization in plant–pollinator relationships is probably the most intensively discussed topic of pollination biology. Phenotypically generalized flowers are typically also considered to be generalized ecologically and/or functionally. Our study focuses on visitors to flowers of Hypericum roeperianum and H. revolutum, two closely related co-flowering Afromontane plants with flat flowers, which can be visited by many insects. We collected insect visitors and recorded their behaviour. Both Hypericum species were visited by large numbers of morphospecies and functional groups, which might indicate that they are highly generalized plants. Nevertheless, after including the visitors’ abundance, behaviour and contact with the plants’ reproductive organs, only a single carpenter bee species could be considered an effective pollinator of H. roeperianum, and a few smaller bee species (mainly Apis mellifera and Meliplebeia ogouensis) could be considered as effective pollinators of H. revolutum. Despite the fact that the flowers appear at first glance phenotypically generalized, both species seem to be ecologically and functionally specialized for bee pollination. Our results indicate that even phenotypically generalized flowers can be functionally and ecologically specialized. More precise knowledge of their visitors’ behaviour is crucial for understanding their pollination systems. Our results cast doubts upon the currently leading opinion that generalization prevails in pollination systems, as such conclusions are based mainly on community-wide studies, which usually do not consider the true role of insect visitors.
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Acknowledgments
We would like to thank the Kedjom-Keku community and particularly Ernest Vunan Amohlon from the SATEC NGO for their kind reception in the Big Babanki village and F. Rooks for English proofreading. The research was supported by the University of South Bohemia (136/2010/P, 168/2013/P), the Ministry of Culture of the Czech Republic (DKRVO 2013/12, National Museum, 00023272), the Czech Science Foundation (14-36098G) and the Institutional Research Support Grant No. SVV 260 087/2014.
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Handling Editor: Katja Hogendoorn.
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Checklist of insect visitors on Hypericum sp. (PDF 15 kb)
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Rarefaction curves and extrapolation of rarefaction (PDF 115 kb)
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Bartoš, M., Tropek, R., Spitzer, L. et al. Specialization of pollination systems of two co-flowering phenotypically generalized Hypericum species (Hypericaceae) in Cameroon. Arthropod-Plant Interactions 9, 241–252 (2015). https://doi.org/10.1007/s11829-015-9378-8
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DOI: https://doi.org/10.1007/s11829-015-9378-8