Paleobotany in the Post-Genomics Era
Tiffney, Bruce H. .
Fossils: A source of ground truth in phylogeography.
BIOGEOGRAPHY is one of the most synthetic of biological undertakings; it requires placing a substantiated phylogenetic model in a geological, climatological and ecological context, all of which shift through time. In short, a reductionist's nightmare. In the past two decades the application of cladistic and molecular techniques has strengthened our grasp upon phylogeny. This has allowed erection of hypotheses of past distribution patterns based upon samples from available living material and algorithms for their interpretation. Fossils have contributed to these cladistic approaches by adding morphological "check points" to character associations in time, but fossil evidence may also serve as an ecological "check point" in space. Assuming physiological uniformitarianism (that fossil and modern taxa united by a common morphology possess similar physiologies), then hypotheses of past distribution must accord with the predicted physiological tolerances of the taxa in question. In its most simple form, a phylogeographic hypothesis is supported by the presence of a fossil in the predicted time and place. However, physiological uniformitarianism suggests that the phylogeographic hypothesis may also be refuted if it places a taxon in an inappropriate ecological setting, e.g., suggests the presence of a palm tree coexisting with a temperate or boreal fossil assemblage. While these tests become more difficult to apply in the Paleocene and earlier due to the increasing frequency of taxa without living physiological parallels, they are particularly useful in evaluating hypotheses involving angiosperm taxa in the Tertiary.
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1 - University of California Santa Barbara, Dept. of Earth Sciences and College of Creative Studies, Santa Barbara, California, 93106, USA
Presentation Type: Symposium or Colloquium Presentation
Date: Wednesday, August 2nd, 2006
Time: 10:45 AM