Murdock, Andrew G. .
Molecular evolution and phylogeny of marattioid ferns, an ancient lineage of land plants.
Understanding the nature of supposed "living fossils" is an important current issue in phylogenetics. The marattioid ferns, long recognized as a distinct lineage of eusporangiate ferns with no close living relatives, are a good case in point. Recent large-scale phylogenies have placed the marattioid ferns as sister to the horsetails (Equisetaceae), however relationships among early branches of the ferns have lacked conclusive support thus far. Despite the putative early-branching position of this lineage in tracheophyte phylogeny, the suggestion that this lineage may represent "living fossils" in both the morphological and molecular senses, the extensive fossil record, and the unique morphological characters that contribute to the charismatic nature of plants in this family, systematists have mostly bypassed working on this family to date. Problems with collection due to the massive size of these ferns, and confusing morphological plasticity exhibited by plants in this family, have resulted in a taxonomic and nomenclatural enigma of daunting proportions, and has contributed to frightening off potential investigators. This research represents the first phylogeny of the family based on DNA sequence data (rps4 with rps4-trnS spacer, trnS-G spacer and trnG intron) combined with morphological data with broad geographic and morphological sampling of the family. Generic definitions, biogeographic history, and preliminary work on rates of molecular evolution within the family will be presented in light of the phylogeny.
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1 - University of California, Berkeley, Department of Integrative Biology, 1001 Valley Life Sciences Bldg. #2465, Berkeley, California, 94720-2465, USA
Presentation Type: Oral Paper
Date: Monday, August 15th, 2005
Time: 9:15 AM