The Comparative - Phylogenetic Method of Reconstructing Evolutionary History
Feild, Taylor S. , Hacke, Uwe G. , Sperry, John S. .
Early functional and ecological evolution of xylem vessels angiosperms and Gnetales; a common theme?
AMONG extant seed plant lineages, angiosperms and Gnetales are the only extant lineages with xylem vessels present in the wood. Recent advances in seed plant phylogenetics suggest that Gnetales and angiosperms are distantly related. If angiosperm and gnetalean vessels are analogous, then can vessels be viewed as a functional motif that evolves whenever the "right" ecological/environmental conditions converge, or are the selective contexts for the origins of mega-porous tubes different in each lineage? Here we integrate new perspectives on the ancestral paleobiology of Gnetales and angiosperms, with an emerging picture of the pathways of early xylem hydraulic functional diversification in Gnetales and angiosperms. Based on physiological functioning in extant basal angiosperm lineages and Gnetum, vessels in both lineages seem to have evolved and diversified under similar (but not exactly the same) conditions of low light and high moisture as well as the evolution of scandent-like habits in both Gnetales and angiosperms. Coupled to functional studies, we discuss how new advances in the phylogenetics and paleobiology of extinct plans will be needed to reign in the specific paleohabitat hypotheses for vessel origins in seed plants.
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1 - University of Tennesee, Knoxville, Ecology and Evolutionary Biology, Knoxville, Tennesee, 37996-1610, USA
2 - University of Utah, Department of Biology, 257 S. 1400 E., Salt Lake City, Utah, 84112, USA
3 - 1969 Loring Ave., San Diego, California, 92109-1406
Presentation Type: Symposium or Colloquium Presentation
Location: 314/Bell Memorial Union
Date: Wednesday, August 2nd, 2006
Time: 3:30 PM