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Abstract Detail


Biogeography

Misiewicz, Tracy [1], Storer, Caroline [2], Zerega, Nyree J C [1].

Investigating the Evolutionary History of the genus Dorstenia (Moraceae).

With 105 species, Dorstenia is the second largest genus within the Moraceae (Mulberry) family (~1100 species), second only to Ficus (~750 species), and the only member of the family with woody, herbaceous and succulent species. With one exception, all Dorstenia species are restricted to the Neotropics and Africa. Dorstenia is also the only genus in the Moraceae family with an almost equal distribution of species on either side of the Atlantic Ocean. This distribution has lead to the hypothesis that Dorstenia originated before Africa and South America split apart from Gondwana approximately 105 million years ago and Dorstenia species on each continent subsequently underwent separate radiations. Alternatively, Dorstenia could have originated post-Gondwana and dispersed or migrated from one continent to the other. We are reconstructing Dorstenia’s phylogeny using DNA sequence data in order to test these biogeographical hypotheses, and to trace the evolution of specific morphological characters, such as the evolution from woody and succulent habits which are thought to be primitive and found only in Old World species to herbaceousness which is found in both New and Old World species. Molecular dating using fossil data and penalized likelihood has been used to date divergence times within the genus and to explore hypotheses for possible dispersal routes and mechanisms. Based on preliminary analysis of a subset of Dorstenia, the genus diverged well after the split of Africa from South America and migrations between the two continents are proposed across the North Atlantic Landbridge during the Eocene.


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1 - Northwestern University, Plant Biology and Conservation, Evanston, IL, 60202, USA
2 - Eckerd College, Biology, St. Petersburg, FL, 33711, USA

Keywords:
Biogeography
Gondwana
Moraceae
Dorstenia
phylogeny
molecular dating.

Presentation Type: Poster:Posters for Topics
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P62005
Abstract ID:2143


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