Whittemore, Alan .
Evolutionary patterns in Celtis subg. Celtis.
Celtis subgenus Celtis is a monophyletic group, containing all of the temperate taxa in the otherwise tropical genus Celtis. Understanding of the group has been hampered by unrealistic assumptions about hybridization, and by the failure to recognize apomixis, which is widespread in the subgenus. All known sexual populations are diploid, while all apomicts are triploid or tetraploid. Apomixis has originated independently multiple times, always with a switch to polyploidy (usually triploidy). The taxonomic pattern is different in North America (where some species are always diploid and sexual and others are always triploid and apomictic), east Asia (where diploid sexual populations and triploid apomictic populations occur in the same species), and southwest Eurasia (where all taxa examined are apomictic, and sexual diploids are unknown). Apomicts can be pollinated by sexual species, producing higher polyploids.
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1 - U. S. National Arboretum, 3501 New York Ave NE, Washington, DC, 20002, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Ballroom D/Convention Center
Date: Monday, August 2nd, 2010
Time: 1:00 PM