Bringing Together the Living and Dead: Integrating Extant and Fossil Biodiversity in Evolutionary Studies
Rydin, Catarina , Pedersen, Kaj Raunsgaard , Wu, Shunqing , Friis, Else Marie .
Homology assessments within the Gnetales: integrating information from molecules, extant morphology and fossils.
THE seed plant group Gnetales (Ephedra, Gnetum and Welwitschia) has a restricted species diversity in the modern world, but several aspects indicate that it most probably stem from an ancient and once much more diverse lineage. Gross morphology and ecology of the extant species show a remarkable similarity within each genus but differs significantly between the genera. Furthermore, extant members of the group have a disjunct geographic distribution, and there is a relatively common occurrence of dispersed "ephedroid" pollen in late Mesozoic sediments. The rapidly expanding knowledge on Mesozoic diversity of the Gnetales, based on megafossils and mesofossils, supports the ancient history of Gnetales, but homology assessments with modern plants are not always straightforward, which complicates assignment of the fossils to subgroups within Gnetales. To find and describe new fossils is an important basis for the understanding of an ancient group. But to be able to take a study one step further and investigate historical relationships and distributions, palaeoecology, or character evolution of a group, a well resolved and supported phylogeny of modern plants is a prerequisite. If the phylogeny is based on molecular data it is also necessary to find morphological synapomorphies for modern subgroups. The large interest in dating extant groups using molecular data and fossil calibration highlights the importance and potential of integrative work. Here we present molecular evidence and new fossil relatives of Ephedra and Gnetum, and discuss our efforts, problems and progresses in bringing together the living and the dead Gnetales, and implications for the understanding of morphology, distribution and age of modern species.
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1 - Swedish Museum of Natural History, Department of Palaeobotany, Svante Arrhenius väg 7, P.O. Box 50007, Stockholm, SE-104 05, Sweden
2 - University of Aarhus, Department of Geology, Universitetsparken, DK-8000, Aarhus, , Denmark
3 - Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, 210008, China
Presentation Type: Symposium or Colloquium Presentation
Location: 134/Performing Arts Center
Date: Tuesday, August 1st, 2006
Time: 2:45 PM