Systematics/Phytogeography / Taxonomie/ Section
Pelser, Pieter B. , Kennedy, Aaron H. , Tepe, Eric J. , Nordenstam, Bertil , Watson, Linda E. .
Ancient reticulation characterizes the evolutionary history of tribe Senecioneae (Asteraceae).
Tribe Senecioneae (Asteraceae) comprises c. 150 genera and 3,100 species, has a worldwide distribution, and shows enormous diversity in morphology and ecology. Phylogenetic analyses using nuclear and plastid DNA sequence data to study the mode and tempo of its diversification reveal that Senecioneae presumably originated in sub-Saharan Africa between 22 and 24 mya. Detailed conclusions about the patterns of diversification of Senecioneae are complicated by incongruent nuclear and plastid phylogenies. Strongly supported conflicting phylogenetic patterns not only affect phylogeny inference of closely related species, but are also found among genera and groups of genera, and even traverse subtribal boundaries. Incongruent phylogenetic hypotheses especially complicate the interpretation of relationships among the main clades of subtribe Senecioneae, the largest subtribe. This potentially indicates widespread reticulation early in the diversification of this subtribe, which may have been caused by extensive hybridization or incomplete lineage sorting as a result of rapid speciation. Preliminary biogeographic and molecular dating studies indicate that this took place in sub-Saharan Africa, perhaps the Cape Floristic Region, between 16 and 19 mya.
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Website of Pieter Pelser
1 - Miami University, Department of Botany, Oxford, Ohio, 45056, USA
2 - University of Utah, Department of Biology, 257 South 1400 East, Salt Lake City, Utah, 84112, USA
3 - Swedish Museum of Natural History, Department of Phanerogamic Botany, P.O. Box 50007, Stockholm, SE-104 05, Sweden
Presentation Type: Oral Paper:Papers for Sections
Date: Wednesday, July 30th, 2008
Time: 4:45 PM