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Abstract Detail


Bringing Together the Living and Dead: Integrating Extant and Fossil Biodiversity in Evolutionary Studies

Lupia Ii, Richard [1], Schneider, Harald [2], Nagalingum, Nathalie S. [3], Pryer, Kathleen M. [3].

Jurassic origin for the Salviniaceae: the last word or just the first?

PHYLOGENETIC analyses have demonstrated that the leptosporangiate heterosporous fern families Marsileaceae (Marsilea, Pilularia, Regnellidium) and Salviniaceae (Azolla and Salvinia) are most closely related to one another—the Salviniales. Read directly from the fossil record, the first appearance of heterosporous ferns reliably dates to the earliest Cretaceous and their radiation is broadly coincident with the radiation of flowering plants and derived ferns. The fossil record of heterosporous ferns is largely composed of dispersed megaspores and microspores. That record is dense enough to permit the application of confidence intervals and stratigraphically constrained phylogenetic analyses to investigate the likely timing of their origins and trace their diversification through time and space. Our morphological phylogenetic analysis including fossil and extant taxa supports the inclusion of Balmeisporites and Ghoshispora in crown group Salviniales, and previous conclusions about a marsileaceous affinity for Arcellites and inclusion of Glomerisporites and Parazolla in Salviniaceae. Confidence intervals with binned, presence/absence data, place the divergence of the lineages leading to the crown groups in the Late Jurassic, consistent with the occurrence of the macrofossil Regnellites in the Berriasian. Combining confidence intervals with our phylogeny also suggests a Late Jurassic origin. However, this analysis may be extended using megaspore occurrence records by geographic region and temporal interval, and a taphonomic control group (heterosporous lycopsids). When divergence times are estimated in light of variation in sampling intensity, a substantially older origin of Salviniales cannot be excluded.


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1 - Sam Noble Ok Museum Natural History, University of Oklahoma, 2401 Chautauqua Avenue, Norman, Oklahoma, 73072, USA
2 - University of Goettingen, Department of Systematic Botany, Albrecht von Haller Institute for Plant Sciences, Untere Karspuele 2, Goettingen, D-37073, Germany
3 - Duke University, Department of Biology, 139 Biological Sciences Building, PO Box 90338, Durham, North Carolina, 27708, USA

Keywords:
divergence time estimates
heterosporous ferns
phylogeny
Sampling bias.

Presentation Type: Symposium or Colloquium Presentation
Session: 57-6
Location: 134/Performing Arts Center
Date: Tuesday, August 1st, 2006
Time: 4:00 PM
Abstract ID:535


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