Systematics/Phytogeography / Taxonomie/ Section
McDill, Joshua , Repplinger, Miriam , Simpson, Beryl , Kadereit, Joachim W. .
Molecular Phylogenies of Linum and the Linaceae, with implications for their classification, biogeographic history, and evolution of heterostyly.
The genus Linum includes approximately 180 species distributed throughout the temperate and subtropical regions of the world. Molecular phylogenetic analyses of chloroplast genes (ndhF and matK) and the nuclear ITS show that the major lineages of the temperate Linaceae, and all five recognized sections of Linum, likely arose in Eurasia, and that Linum is not monophyletic. The blue-flowered flaxes, including the cultivated flax, L. usitatissimum, are shown to be a monophyletic group that has moved out of Eurasia on at least two occasions, once to North America and once to Australia. Sister to the blue-flowered flaxes is a lineage that includes the remaining, predominantly yellow-flowered sections of Linum as well as Hesperolinon, Sclerolinon, Cliococca, and Radiola. The North American, South American, and South African species groups of this “yellow-flowered” lineage appear to have originated from a single Eurasian ancestor. The South American and South African groups are each monophyletic, indicating probable single colonization events with subsequent diversification in these areas, but their relationships to members of the large North American group are unclear. Ancestral state reconstructions using parsimony and maximum likelihood show that, while heterostyly might have arisen multiple times in the Linaceae and in Linum, it cannot be ruled out as the ancestral state for the entire family, with multiple reversions to homostyly resulting in the pattern observed today.
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1 - University of Texas at Austin, Plant Resources Center and Section of Integrative Biology, 1 University Station A6720, Austin, Texas, 78712, USA
2 - Johannes Gutenberg-Universitaet Mainz, Institut fuer Spezielle Botanik und Botanischer Garten, Mainz, Germany
ancestral state reconstruction
Presentation Type: Oral Paper:Papers for Sections
Date: Wednesday, July 30th, 2008
Time: 3:15 PM