Land Plant Evolution: Phylogenetics and Beyond
Renzaglia, Karen S. .
Land plant evolution from the spermís eye view.
THE terrestrial environment placed severe constraints on strategies and structures associated with sexual reproduction in land plants. Naked, free-swimming male gametes are perhaps the most vulnerable cells produced during the life cycle of any embryophytes. These tiny fragile cells display an unparalleled level of complexity both in development and structure. Gamete evolution is characterized by dramatic restructuring in every major clade of bryophytes and pteridophytes. In this presentation we will compare motile gamete architecture across land plants and will present new three-dimensional reconstructions of gametes for key taxa such as Haplomitrium. We will examine how these intricate cells inform our understanding of both land plant relationships and the evolution of cell structure. Early studies of spermatogenesis predicted phylogenetic conclusions that were later supported by molecular analyses. Scrutiny of gamete architecture based on well-supported phylogenies reveals unique lines of specialization within clades, including three independent transitions from biflagellated to multiflagellated cells. Further examinations of gamete ontogeny and microstructure in phylogenetically significant taxa will continue to deepen our understanding of biodiversity and character evolution in early embryophytes.
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1 - Southern Illinois University, Department of Plant Biology, 1125 Lincoln Drive, Carbondale, Illinois, 62901-6509, USA
Presentation Type: Symposium or Colloquium Presentation
Date: Monday, July 31st, 2006
Time: 3:55 PM