Metzgar, Jordan S. , Skog, Judith E. , Zimmer, Elizabeth , Pryer, Kathleen M. .
Is Osmunda paraphyletic?
OSMUNDACEAE is an ancient family sister to all other leptosporangiate ferns and familiar to botanists and horticulturists alike. Although the family has only 16 extant species, it possesses a rich fossil record of about one hundred extinct taxa. Historically, three living genera have been recognized: Osmunda, Todea and Leptopteris. Although Todea and Leptopteris are undoubtedly monophyletic, there has been some question regarding the monophyly of Osmunda. It has traditionally been divided into three subgenera (Osmunda, Plenasium and Osmundastrum) but morphological studies have been unable to clearly resolve the circumscription of these. The most persistent problem has involved the placement of O. cinnamomea. A recent rbcL analysis of Osmundaceae placed O. cinnamomea as sister to the rest of the family, thereby rendering Osmunda paraphyletic. Here we use data from seven plastid loci to evaluate relationships within Osmundaceae, and our findings concur with those of the single-gene study. The paraphyly of Osmunda could be resolved by recognizing O. cinnamomea as a new genus and narrowing the circumscription of Osmunda to all other species in the genus. We also estimate the timing of key divergences within the family by applying fossil constraints to well-supported nodes in our phylogeny.
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1 - Duke University, Department of Biology, 139 Biological Sciences Building, PO Box 90338, Durham, North Carolina, 27708, USA
2 - National Science Foundation, Division of Biological Infrastructure, 4201 Wilson Blvd., Arlington, Virginia, 22203, USA
3 - Smithsonian Museum Support Centre, Laboratories of Analytical Biology, 4210 Silver Hill Road, Suitland, Maryland, 20746, USA
divergence time estimates.
Presentation Type: Oral Paper:Papers for Sections
Date: Tuesday, August 1st, 2006
Time: 9:00 AM