Colloquium: Assembling the Tree of Life Colloquium
Rothwell, Gar W. .
Anthophytes and seed ferns in the origin of flowering plants; contemporary approaches to the resolution of relationships.
Over the past decade there has been an intriguing divergence of results from some phylogenetic analyses that include either a combination of living and extinct taxa or only living taxa to resolve deep internal nodes of the polysporangiophyte (≈ vascular plant) tree of life. Several interesting patterns are beginning to emerge. Some clades that consistently attach near the tips of branches in the results of studies that include both fossils and living species are routinely placed at basal nodes of trees that are resolved using living species only. Other clades that appear relatively late in the fossil record consistently resolve as the sister group to clades with much more ancient fossil records. Examples of such discrepancies include the positions of angiosperms and/or gnetophytes on the seed plant tree and of Pinaceae among other families of conifers. There also is a positive correlation between long branches and taxa that most frequently are responsible for divergent results. Because extinct clades with novel combinations of characters have the potential to dissect long branches, some paleobotanical studies are focusing on recently described extinct species to aid in the discovery of previously unrecognized spermatophyte clades. Phylogenetic relationships of newly hypothesized clades of seed ferns and putative anthophytes are evaluated using subsets of the 375+ character morphological matrix developed by the gymnosperm AToL consortium, and are presented as examples for assessing the results of analyses that combine different data sets for resolving deep internal nodes of the vascular plant tree.
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Gymnosperm AToL web site
1 - Ohio University, Department of Environmental and Plant Biology, Athens, OH, 45701, USA
seed plant phylogeny.
Presentation Type: Symposium or Colloquium Presentation
Location: Cottonwood C/Snowbird Center
Date: Tuesday, July 28th, 2009
Time: 1:15 PM