Ley, Alexandra , Claßen-Bockhoff, Regine .
Parallel evolution of plant-pollinator interactions in African Marantaceae.
THE Marantaceae (about 31 genera, 550 species) are a pantropically distributed family of herbs and lianas from the order Zingiberales. An important feature of the family is the irreversible explosive pollination mechanism with secondary pollen presentation. 80% of the species occur in America, 11% in Asia and 9% in Africa. Africa is believed to be the continent of origin. Its species belong to at least five different clades occupying basal and advanced positions in the phylogenetic tree. While ecological investigations have predominantly been conducted in America, no data are actually available from the African Marantaceae. Field investigations in Gabon (34 ssp.) have elucidated a remarkable high floral diversity which is correlated with a diverse range of specialised plant-pollinator interactions. The latter include pollinators such as Amegilla, Halictidae, Xylocopa, nectarbirds and probably moths. Pollination and bagging experiments have shown that all species are self-fertile. Only two species are autogamous, while all other species depend on animals to transfer their pollen onto the stigma. Pollen is densely packed with a P/O-ratio of (2,2 -) 35 to 140 which might be a hint to a precise pollen transfer mechanism during the single pollination chance of each flower. Despite self-compatibility and the specialised plant-pollinator interactions the fruit set of African Marantaceae is low at around 10%. This is probably due to a high rate of herbivory, fruit abortion, pollinator limitation and ineffective floral visits. Considering the phylogenetic background, a strong parallel evolution in floral morphology and plant-pollinator interactions becomes apparent among the two larger clades obviously indicating similar selection pressures in the course of evolution.
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1 - Johannes-Gutenberg-Universität Mainz, Institut für Spezielle Botanik und Botanischer Garten, Mainz, 55099, Germany
Presentation Type: Oral Paper:Papers for Topics
Date: Monday, July 31st, 2006
Time: 3:30 PM