Colloquia: Emerging Results from Studies of Gymnosperms on the Tree of Life II
Rydin, Catarina , Ickert-Bond, Stefanie M. .
Ephedran evolution: re-radiation in the Cenozoic after a bottleneck effect.
Early Cretaceous fossils, which share uniquely derived features with extant Ephedra (Gnetales) have been known for some time. It has not been possible to assign them to any particular subclade within Ephedra, but in some cases, it has also not been possible to separate them from the extant genus by any character. Consequentially, these fossils have been of limited use for further studies and the timing of evolutionary events in Ephedra has been uncertain. Morphological variation in Ephedra is limited and apparently confusing from an evolutionary perspective with parallelisms and intra-specific variation. However, recent integrative studies based on molecular data, morphology, micromorphology, anatomy and histology show that there is little evidence for an inclusion of the Cretaceous fossils in the extant clade. Extant diversity seems to be the result of a new radiation, which took place after the K-T boundary. Interestingly, this second radiation has not been manifested in terms of morphological evolution or latitudinal habitat preferences. Notwithstanding striking similarities between living and Cretaceous Ephedra, available data indicate that the Mesozoic diversity went almost entirely extinct in the late Cretaceous causing a bottleneck effect in Ephedra, reflected still today by an extraordinarily low amount of genetic and structural diversity.
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1 - Stockholm University, Department of Botany, Lilla Frescativägen 5, Stockholm, SE-10691, Sweden
2 - University of Alaska Fairbanks, Department of Botany, 907 Yukon Drive, Fairbanks, AK, 99775, USA
Presentation Type: Symposium or Colloquium Presentation
Location: Ballroom C/Convention Center
Date: Monday, August 2nd, 2010
Time: 1:00 PM