AOBPreview published online on May 13, 2009
Annals of Botany, doi:10.1093/aob/mcp106
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Pollination syndromes in African Marantaceae
Institut für Spezielle Botanik und Botanischer Garten, Johannes Gutenberg-Universität Mainz, Germany
* For correspondence. E-mail aley{at}uni-mainz.de
Received: 3 September 2008 Returned for revision: 16 October 2008 Accepted: 25 March 2009
Background and Aims: The Marantaceae (550 spp.) is the most derived family in the order Zingiberales and exhibits a complex explosive pollination mechanism. To understand the evolutionary significance of this unique process of pollen transfer, comparative morphological and ecological studies were conducted in Gabon.
Methods: During a total stay of 11 months, 31 species of Marantaceae were investigated at different sites in Gabon. The study included analyses of floral diversity, observations on the pollinator spectrum as well as ecological measurements (e.g. nectar sugar concentration and volume).
Key Results: Analyses reveal five flower types based on flower size and pigmentation, spatial arrangement of the floral tube and presence/absence of nectar guides and conspicuous outer staminodes. Each type is associated with a specific functional pollinator group leading to the description of distinct pollination syndromes. The small (horizontal) flowers are predominantly pollinated by small bees (Thrinchostoma spp., Allodapula ornaticeps), the large (horizontal) and medium-sized (horizontal) flowers by medium-sized bees (Amegilla vivida, Thrinchostoma bicometes), the locked (horizontal) flowers by large bees (Xylocopa nigrita, X. varipes) and the (large) vertical flowers by sunbirds.
Conclusions: The longevity of Marantaceae individuals and the omnipresence of their pollinators allowed the specialization to a given functional pollinator group. Intermediate ecological values, however, make occasional pollinator overlaps possible, indicating potential pathways of pollinator shifts. Similar radiation tendencies observed on other continents hint at similar selective pressures and evolutionary constraints.
Key words: Africa, floral diversity, functional pollinator groups, Gabon, Marantaceae, nectar, plant–animal interaction, pollination syndromes