Ephedra pollination and other gnetalean oddities
Bolinder, Kristina , Alexandersson, Ronny , Ickert-Bond, Stefanie M. , Ehrlén, Johan , Rydin, Catarina .
Cenozoic evolution in Ephedra: Did a shift from biotic to abiotic pollination drive diversification?
Recent findings indicate that at least two major diversification periods have occurred during the evolutionary history of Ephedra (Gnetales). In the Early Cretaceous, a comparatively large diversity of ephedroids was present, including species that share uniquely derived features with extant Ephedra. A significant part of this diversity seemingly went extinct in the Late Cretaceous and in the early Paleogene causing a bottleneck effect still evident in the group today. Another period of diversification, which started presumably 30 million years ago, gave rise to the present-day species diversity characterized by an extraordinarily small amount of genetic and structural diversity. An intriguing question is what caused this diversification period. Based on current understanding of extant and fossil ephedran diversity, a key morphological innovation or range expansion to a new latitudinal zone both appear unsatisfactory as explanations. Another possible hypothesis is a shift in pollination mechanism. Biotic pollination and co-evolution with pollinatorsis considered a possible explanation for the evolutionary success of angiosperms.Perhaps less known is that biotic pollination also occurs in gnetalean gymnosperms, e.g., in Welwitschia and studied species of Gnetum.While Ephedra is most often regarded as wind pollinated, there is evidence indicating a possible variation in pollination syndrome within the genus. This is also supported by a variation in key morphological features of the male cones. We performed a comprehensive field study of the pollination mechanisms of two sympatric but distantly related species of Ephedra from Greece, E. foeminea and E. distachya. Our results suggest that E. foeminea (the sister to all other living Ephedra species) is primarily entomophilous and E. distachya (nested with-in the crown-group Ephedra) primarily anemophilous. This supports the hypothesis that a shift in pollination mechanism occurred during the evolutionary history of Ephedra. Is it possible that a shift from biotic to abiotic pollination resulted in a diversification that saved Ephedra from extinction?
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1 - Stockholm University, Botany, Lilla Frescativägen 5, Stockholm, SE-106 91, Sweden
2 - Uppsala University, Evolutionary Biology Centre, Norbyvägen 14, Uppsala, SE-752 36, Sweden
3 - University Of Alaska Museum Of The North, Herbarium (ALA) And Dept. Of Biology And Wildlife, University Of Alaska Fairbanks, 907 Yukon Dr., Fairbanks, AK, 99775, USA
4 - Stockholm University, Lilla Frescativägen 5, Stockholm, SE 10691, Sweden
5 - Stockholm University, Department of Botany, Stockholm, se-106 91, Sweden
Presentation Type: Symposium or Colloquium Presentation
Location: Delaware A/Hyatt
Date: Monday, July 9th, 2012
Time: 8:30 AM