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Pteridological Section/AFS

Rai, Hardeep [1], Graham, Sean W. [1].

Inference of higher-order relationships of extant ferns and relatives using plastid genome data.

Current molecular phylogenetic studies reveal a single "moniliform" clade, consisting of ferns and (most of) their extant allies. This clade, equivalent to all of the living pteridophytes bar the lycophytes, includes the leptosporangiate ferns (a large clade of ~33 families), two clades of eusporangiate ferns (Marattiaceae and Ophioglossaceae), Equisetaceae (horsetails) and Psilotaceae (whisk ferns). Considerable potential for the recovery of artifactual deep relationships is apparent in the seed plants, the sister group of moniliforms in molecular studies. We explored whether there may be a similar potential for mis-inference of moniliform higher-order relationship, using a new data set that is based on a sampling of a large fraction of the plastid genome per taxon. We observed strong support (high bootstrap values, bayesian posterior probabilities) for most relationships among exemplar moniliforms, and our initial results are generally compatible with those of other recent molecular studies. However, we also noted a worrying potential for strong incongruence among data partitions for a subset of clades. A major structural mutation (intron presence vs. absence) is apparently shared by all eusporangiate moniliforms, but this may reflect parallel loss events. Our study is partly aimed at making a robust inference of the major branches of leptosporangiate fern phylogeny. We generally recovered improved support along this backbone, including several clades that to date have had only weak or moderate support.


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1 - University of British Columbia, Botanical Garden And Centre For Plant Research, 6804 Sw Marine Drive, Vancouver, British Columbia, V6T 1Z4, Canada

Keywords:
moniliforms
vascular plants
Pteridophytes
eusporangiate ferns
leptosporangiate ferns
Ferns
plastid genomes
error
bias
incongruence
tree of life
intron loss.

Presentation Type: Oral Paper
Session: 5-4
Location: 602/Hilton
Date: Monday, August 15th, 2005
Time: 9:30 AM
Abstract ID:434


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