Systematics Section / ASPT
Jian, Shuguang , Soltis, Pamela S. , Dhingra, Amit , Li, Ruiqi , Qiu, Yin-Long , Yoo, Mi-Jeong , Bell, Charles , Soltis, Douglas E. .
Phylogenetic relationships and diversification within Saxifragales based on molecular data.
DESPITE the use of five genes in previous studies, deep-level phylogenetic relationships within Saxifragales remain enigmatic, apparently the result of ancient, rapid radiation and/or extinction. To elucidate relationships within Saxifragales, we constructed two new data sets. The first involved 17 genes (38,000 bp), for 25 taxa. We also amplified and sequenced the entire inverted repeat (26,120 bp) for a smaller number (15) of taxa. These analyses revealed that Peridiscaceae, Altingiaceae, Cercidiphyllaceae, Hamamelidaceae, and Daphniphyllaceae are sisters to the remainder of the clade (Paeoniaceae, Crassulaceae, Haloragaceae, Iteaceae, Pterostemonaceae, Grossulariaceae, and Saxifragaceae). These results are supported by morphological data. Peridiscaceae, Altingiaceae, Cercidiphyllaceae, Hamamelidaceae, and Daphniphyllaceae are woody and share anatomical features including vessels with scalariform perforation plates, imperforate tracheary elements with distinctly bordered pits, and wood parenchyma that is apotracheal and diffuse. In contrast, these features either do not occur, or occur rarely, in other Saxifragales, which are primarily herbaceous (e.g., Crassulaceae, Saxifragaceae), or shrubs. We estimated the age of Saxifragales, as well as the ages of major clades within Saxifragales, using penalized likelihood with and without age constraints. We calibrated the trees using several internal points corresponding to well-characterized fossils of Cercidiphyllaceae, Altingiaceae, and Hamamelidaceae. With PL, the age estimates of Saxifragales range from 76.10-87.40 mya (without constraints). A Bayesian method gave younger estimates, 72.01-89.66 mya (without constraints) to 91.31 – 97.15 mya (with constraints). The early diversification of the clade proceeded rapidly, with the ages of Hamamelidaceae, Altingiaceae, and Cercidiphyllaceae falling within several million years of the age of the clade. The herbaceous Saxifragales diversified more recently.[c.e.:srb]
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1 - University of Florida, Department of Botany, 220 Bartram Hall, P.O. Box 118526, Gainesville, Florida, 32611-8526, USA
2 - University of Florida, Department of Botany, Florida Museum of Natural History, P.O. Box 117800, Gainesville, Florida, 32611-7800, USA
3 - University of Florida, Horticultural Sciences Department, P.O. Box 110690, Gainesville, Florida, 32611, USA
4 - University of Michigan, Department of Ecology & Evolutionary Biology, 830 North University Avenue, Ann Arbor, Michigan, 48109-1048, USA
5 - University of Massachusetts, Department Ecology & Evolutionary Biology, 830 N University Ave, Ann Arbor, Michigan, 48109, USA
6 - Florida State University, School of Computational Sciences, Tallahassee, Florida, 32306, USA
Presentation Type: Oral Paper:Papers for Sections
Location: 144/Performing Arts Center
Date: Tuesday, August 1st, 2006
Time: 12:15 PM