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Abstract Detail


Evolution and Diversification in the Sapindales

Muellner, Alexandra N. [1], Savolainen, Vincent [2], Samuel, Rosabelle [3], Chase, Mark W. [2].

The mahogany family “out of Africa” and round the world: DNA, fossils and diversity.

We report on a global biogeographic study of Meliaceae (“mahogany family”) based on chloroplast gene rbcL, covering all subfamilies, all tribes, and nearly all genera. Together with information on Meliaceae fossils and extant distribution of diversity and endemism in the family, our study indicates that (1) Meliaceae are of western Gondwanan origin; (2) dispersal played an important role for the current distribution of mahogany biota; and (3) the direction of dispersal was most likely an “out-of-Africa” scenario with important dispersal routes across Eurasia and between Eurasia and North America provided by Beringia and the North Atlantic land bridge, and between North America and South America via island chains and/or direct land connections. Fruit and seed fossil findings from Senegal, dating back to the Campanian/Maastrichtian boundary and thus constituting the potentially oldest fossil records of Meliaceae, support the “out-of-Africa” scenario. The implication that the mahogany family originated and began to diversify in Africa is also consistent with high levels of diversity and endemism found in Africa and Madagascar. Due to the stable climatic conditions of Asian terranes over long periods in earth history and their suitability for tropical angiosperms, some of these regions seem to have provided an important sink and secondary source area for extant Meliaceae diversity. During their biogeographic history, Meliaceae populations in North America, Europe, and East Asia were presumably eliminated as tropical climates disappeared from these areas during the Miocene and later epochs. This is corroborated by the lack of Meliaceae fossils in these areas after the Miocene. Our findings confirm that the entry of megathermal, i.e. frost-intolerant, angiosperms into southern continents from Oligocene to Pliocene must be considered as an important means of establishing pantropical distribution patterns.


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1 - Research Institute Senckenberg, Department of Botany and Molecular Evolution, Grunelius-Moellgaard Laboratory, Senckenberganlage 25, Frankfurt, D-60325, Germany
2 - Royal Botanic Gardens, Kew, Jodrell Laboratory, Molecular Systematics Section, Richmond, Surrey, TW9 3DS, United Kingdom
3 - University of Vienna, Faculty Center Botany, Dept. of Systematic and Evolutionary Botany, Rennweg 14, Vienna, A-1030, Austria

Keywords:
Biogeography
dispersal
Fossil constraints
Mahogany
Meliaceae
Molecular clock
Relaxed clock
Sapindales.

Presentation Type: Symposium or Colloquium Presentation
Session: C01
Location: Boulevard B/Hilton
Date: Tuesday, July 10th, 2007
Time: 8:00 AM
Number: C01001
Abstract ID:1124


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