Ephedra pollination and other gnetalean oddities
Rydin, Catarina , Ickert-Bond, Stefanie M. .
Ephedra pollination and other gnetalean oddities.
The gymnospermous Gnetales are well-known and of general interest to botanists because they are pivotal to a better understanding of an important, yet still unresolved question in plant biology: seed plant phylogeny. The Gnetales are considered odd and have repeatedly been described as "enigmatic" and "the lure and despair of the morphologist". A possible reason for this struggle is that extant species comprise only a small fraction of the historical diversity of the group. In recent years, the understanding of diversity, morphology and evolution in the Gnetales has expanded dramatically. Many new fossils have been described, and these fossils have inspired new studies also on extant representatives. Integrative work and contributions from different fields have thus increased understanding of evolutionary patterns, historical events as well as recent adaptations. In Ephedra (Gnetales), integrative studies of fossils and living plants have shown that although the group as a whole and the evolution of some diagnostic traits are of Cretaceous origin, extant diversity is the result of a comparatively recent re-radiation, which began about 30million years ago. Interestingly, this second radiation seems not associated with any obvious key morphological innovations or dramatic changes in latitudinal habitat preferences, i.e., tolerated climatic conditions. There are, however, some still unconfirmed indications that the re-radiation in Ephedra coincided in time with a change in character(s) relevant for pollination. Is it possible that the group escaped from extinction by a shift from biotic to abiotic pollination? Testing this hypothesis involves a number of new investigations, which are currently in progress. Field studies document insect interactions (if any) and the mode of pollination in key species of Ephedra. Properties and function of pollen vectors (wind, insects), and of the pollination droplets produced by Ephedra cones, are investigated using new analytical approaches. Preliminary results of these studies have highlighted the need for additional studies of anatomy and morphology of reproductive and vegetative structures. Further, newly described fossils add to the knowledge of former diversity in the Gnetales. The symposium on ephedran pollination and gnetalean evolution in time and space will include talks by senior scientists, postdocs and graduate students from the United States, Canada, Mexico and Europe. It is truly inter-disciplinary; neobotanical systematics meets ecology and entomology, physiology, and palaeobotany.
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1 - Stockholm University, Department of Botany, Stockholm, se-106 91, Sweden
2 - UA Museum Of The North, Museum Of The North Herbarium, 907 Yukon Dr., Fairbanks, AK, 99775, USA
seed plant phylogeny.
Presentation Type: Symposium or Colloquium Presentation
Location: Delaware A/Hyatt
Date: Monday, July 9th, 2012
Time: 8:00 AM