Principles of crucifer evolution
Jordon-Thaden , Ingrid Eastman , Koch, Marcus A. .
The evolutionary history of Draba - insights into a worldwide-distributed polyploid complex.
The genus Draba L. (Brassicaceae) is an ideal model system to study arctic and alpine adaptation and polyploid speciation. We have shown the global alpha diversity of Draba has its area of highest diversity in the Central Rocky Mountains, while its center of genetic diversity and origin of the genus is the Caucasus Mountains, determined from our phylogenetic analysis of ITS and trnL-F. Its ploidy level ranges from diploid to tetradecaploid (14x), and has accelerated speciation and polyploidization rates compared to other perennial species. Our phylogeny of the genus led to the re-circumscription of some North and South American annual Draba and will be renamed to new genera. The phylogeography of Draba has led us to understand that its age is less than 3 million years old, and has migrated globally during the glaciation cycles of the Quaternary. From the evidence collected thus far, it is apparent that Draba is currently in the process of speciating in parts of its distribution, especially in the Central Cordillera of North America (i.e. Greater Rocky Mountains). This region has been defined by our research to be a suture zone of old and new Draba lineages. In order to study alpine Draba reproduction and genetics, in greenhouse trials, reproductive modes were investigated for self-compatibility and incompatibility (observations were made from 35 globally distributed species). In addition, D. oligosperma,an octaploid apomict that is distributed from Alaska to Arizona in the North American Cordillera, was fully determined to be an apomict with flow cytometric seed screens and light microscopy of ovules for embryogenesis analysis. Further research on the population genetics and parentage of D. oligosperma is being done. This presentation will give an overview on these data, and will discuss the overall use of Draba for the study of polyploid speciation and evolution.
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1 - University Of Florida, Biology, Bartram-Carr Hall, POBox 118525, Gainesville, FL, 32605, USA
2 - Centre for Organismal Studies Heidelberg, Heidelberg University, Biodiversity and Plant Systematics, Im Neuenheimer Feld 345, Heidelberg, 69120, Germany
Presentation Type: Symposium or Colloquium Presentation
Location: Delaware C/Hyatt
Date: Tuesday, July 10th, 2012
Time: 4:30 PM