Tropical Biology Section
Vary, Laura B. , Lowry, Porter P. II , Rabehevitra, David , Randrianjanahary, Mirana , Schatz, George E. .
Breeding systems of the littoral forests of Madagascar.
The littoral forests of Madagascar are a rich and distinctive community, with 13% of the total Malagasy flora (~13,000 – 14,000 estimated angiosperm species) represented in an area covering < 1% of the total land surface of the island. While many recent studies have focused on individual taxonomic groups, the floral biology of the Malagasy flora has never been examined in detail. As part of a larger study of breeding system diversity in the entire flora, we studied the incidence of various breeding systems and their ecological correlates (e.g. habit, flower color/size, fruit type, fruit disperser) using the littoral forest flora as a well-studied, representative sample. Using taxonomic literature, herbarium specimens and field observations, we tabulated the breeding systems of the 1,511 angiosperm species recorded from littoral forests. The majority are monomorphic (68.2% hermaphroditic, 8.9% monoecious, 0.8% andromonoecious and 0.6% gynomonoecious); however, dimorphism is more common than for angiosperms as a whole and is represented only by dioecy (18.4% dioecious). Dioecy and monoecy are over-represented among woody species and species with plain flowers (under <10mm and/or drab color). However, dioecy is over-represented among species with fleshy fruit, whereas monoecy is over-represented among dry-fruited species. For species with data on fruit dispersers (N = 89), dioecious species are predominantly dispersed by lemurs and other mammals (88% by lemurs, bats and rats; 36% exclusively by lemurs) and only 8% are exclusively dispersed by birds. Given the high levels of dioecy in Malagasy littoral forests, further studies on the origins of dioecy in the entire Malagasy flora would provide a rare opportunity to test hypotheses on its evolution and high incidence in tropical island floras.
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1 - University of California, Irvine, Ecology and Evolutionary Biology, 321 Steinhaus Hall, Irvine, California, 92697, USA
2 - Missouri Botanical Garden, P.O. Box 299, St. Louis, Missouri, 63166
3 - Missouri Botanical Garden, Madagascar Research and Conservation Program, b.p. 3391, Antananarivo, 101, Madagascar
4 - Missouri Botanical Garden, Po Box 299, St Louis, Missouri, 63166-0299, USA
Presentation Type: Poster:Posters for Sections
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM