Ranker, Tom A. , Sundue, Michael A. .
Molecular phylogenetics of grammitid ferns: global biogeographic perspectives.
Grammitid ferns comprise a monophyletic group of 900 species of tropical, forest-dwelling epiphytes. One of the long-standing challenges in the study of grammitid ferns has been the circumscription of genera, with some authors recognizing a single genus and others up to 24. Molecular phylogenetic studies have shown that several large genera occurring mostly in the Paleotropics (Ctenopteris s.l., Grammitis s.l.) or mostly in the Neotropics (Lellingeria, Terpsichore) were polyphyletic, necessitating nomenclatural innovations at the generic level. Although recent taxonomic and phylogenetic studies have made significant progress in delineating primarily Neotropical genera, relatively little progress has been made in the Paleotropics, which holds about 2/3 of the diversity of the clade. We have conducted phylogenetic analyses of DNA sequence data on 295 accessions of grammitid ferns representing 253 species. Neotropical species account for 161 of the accessions and Paleotropical account for 134. These analyses were based on the plastid DNA sequences of rbcL, atpB,and trnL-trnF intergenic spacer. There are several important features of our analyses: 1) A Paleotropical clade was supported as monophyletic (posterior probability support of 0.92).This clade is estimated to comprise ~500 species (two-thirds of all grammitids). It is restricted to Asia and the Pacific except for a single dispersal to Southern Chile (Grammitis magellanica). African and Madagascan species are not part of this clade, they are all disjunctions from otherwise Neotropical genera (Alansmia, Ceradenia, Enterosora,Melpomene, Stenogrammitis, and Zygophlebia) or from the circumaustral Grammitis s.s.; 2) Several Paleotropical genera, as sampled so far, were supported as monophyletic (i.e., Calymmodon, Chrysogrammitis, Dasygrammitis, Scleroglossum, and Xiphopterella); but, 3) several genera were either clearly not monophyletic (e.g., Ctenopterella, Grammitis, Prosaptia, Micropolypodium, Radiogrammitis, and Tomophyllum) or there was insufficient resolution to infer relationships or circumscriptions (e.g., Oreogrammitis and Themelium); 4) The three plastid sequences analyzed provided less phylogenetic resolution among Paleotropical taxa than among Neotropical taxa, although some of the lack of resolution may be due to missing data.
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1 - University of Hawaii at Manoa, Department of Botany, 3190 Maile Way, Room 101, Honolulu, HI, 96822, USA
2 - University of Vermont, Department of Plant Biology, 111 Jeffers Hall, Burlington, VT, 05405, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Waterman Room/Chase Park Plaza
Date: Monday, July 11th, 2011
Time: 11:30 AM