Colloquium: The Utility of Pollen in Systematic and Morphological Studies: A Celebration of the Life of John J. Skvarla
Ickert-Bond, Steffi , Kurmann, Marie , Rothwell, Gar W. .
Utility of pollen characters in gymnosperm systematics and Assembling the Tree of Life (AToL).
Within the field of plant taxonomy and palynology John Skvarla's interests are wide and range from pollen morphology, palaeopalynology to pollen ontogeny. While he is mostly recognized for his work on angiosperm pollen, his excellent contributions to the study of gymnosperm pollen together with John Rowley and Bjorn Walles are seldom cited. To examine evolution of pollen type (saccate vs. non-saccate) and infractectal structure (granular vs. alveolar) in gymnosperm pollen we used a broad backbone of gymnosperm phylogeny from a survey of 15-17 plastid loci by Hardeep et al. We constrained the phylogeny with several hypotheses of higher-order phylogenetic relationships in gymnosperms (e.g., “gnepine”, “gnetifer”, “Gnetales sister”) and used pollen characters from a newly constructed morphological matrix for seed plants, including both extant and extinct taxa, to evaluate how these hypotheses differ in reconstructing pollen evolution in gymnosperms. The inclusion of fossils in phylogenetic analyses may help to resolve disputes among competing hypotheses based solely on extant taxa. For example, there are two competing hypotheses specifying the original pollen type in gymnosperms, one of which assumes saccate pollen was ancestral in crown-group conifers, while the other places non-saccate pollen at the base of the stem-lineage of conifers. While fossils do not seem to provide signals crucial to recovering a robust phylogeny, they are critical to understanding the evolution of key features of pollen evolution in gymnosperms.
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1 - University of Alaska Fairbanks, Department of Biology and Wildlife and UA Museum, 907 Yukon Dr., Fairbanks, Alaska, 99775-6960, U.S.A.
2 - Ausserdorf 29, Altburon, CH-6147, Switzerland
3 - Ohio University, Department of Environmental & Plant Biology, Porter Hall, Richland Avenue, Athens, Ohio, 45701-2979, USA
Presentation Type: Symposium or Colloquium Presentation
Location: Fort Camp Lounge/Gage
Date: Tuesday, July 29th, 2008
Time: 2:00 PM