Colloquia: Systematic and Evolutionary Perspectives on Apomixis
Grusz, Amanda L. , Windham, Michael , Pryer, Kathleen M. .
Examining the role of apomixis in the evolution of desert-adapted ferns.
Ferns are known for exhibiting significant levels of polyploidy and apomixis, yet the impact of these phenomena on their evolution and diversification remains poorly understood. Perhaps the most direct attempt to elucidate the impact of these factors on fern diversification has been undertaken in the cheilanthoid ferns. This group of ferns comprises a taxonomically, geographically, and cytogenetically diverse clade in which more than 50% of the species are neopolyploids and approximately 25% are apomictic polyploids. Cheilanthoids have taken an unusual evolutionary pathway relative to other ferns; they represent one of the few lineages that colonize and thrive in xeric terrestrial habitats. To achieve this, they have developed various morphological, physiological, and reproductive mechanisms to withstand the seasonal (or long term) droughts characteristic of desert environments. Apomixis is a critical adaptation in this regard because it allows these ferns to circumvent sexual reproduction, a process that requires water through which sperm can swim to the egg. Apomixis also shortens the life cycle (allowing more rapid establishment of new sporophytes) and significantly improves dispersability within lineages where most of the sexual diploids are obligate outcrossers. The substantial success and observed allelic diversity of apomictic cheilanthoid ferns suggest the existence of underappreciated mechanisms that function to generate genetic diversity and insure long-term adaptability. Here, we investigate patterns and processes of apomixis across the cheilanthoid ferns, with a specific focus toward exploring (1) sources of genetic variation within apomictic polyploid lineages, and (2) the intriguing possibility that apomixis may play a role in the stabilization of paleopolyploid lineages.
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1 - Duke University, Department of Biology, 139 Biological Sciences Building, PO Box 90338, Durham, North Carolina, 27708, USA
2 - Duke University, Department of Biology, 139 Biological Sciences Building , PO Box 90338, Durham , NC, 27708, USA
Presentation Type: Symposium or Colloquium Presentation
Location: 551A/Convention Center
Date: Wednesday, August 4th, 2010
Time: 3:45 PM