Majure, Lucas C. , Soltis, Pamela S. , Judd, Walter S. , Soltis, Douglas E. .
Is Opuntia humifusa monophyletic? Insights from the plastid genome.
Opuntia humifusa is a widespread, polymorphic taxon in Cactaceae distributed over most of the eastern and midwestern United States. Current taxonomic treatments suggest that O. humifusa is a single widely distributed species. However, morphological, cytological, and molecular data from the plastid genome provide evidence that O. humifusa is not monophyletic and that more than one species should be recognized. Both diploid (2n = 22) and tetraploid (2n = 44) cytotypes have been identified. The tetraploid cytotype occurs over a large area in the interior of the eastern and midwestern United States and has mostly yellow flowers with red or orange-red centers, while the diploid cytotype is mostly restricted to the coastal plain of the southeastern United States and has completely yellow flowers in all populations. Phylogenetic analyses of the diploid and tetraploid cytotypes, as well as other members of the O. humifusa complex, resolve the diploid populations in a southeastern clade, while the tetraploid populations consistently group with polyploid taxa from the southwestern United States (which may or may not form a clade). The polyploid lineage may be derived from a genome duplication event that occurred in the common ancestor shared with the diploid members of the O. humifusa complex. This provides evidence that polyploidy has led to speciation and subsequent lineage diversification in this group of Opuntia.
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1 - University of Florida, Department of Biology, Florida Museum of Natural History, P.O. Box 117800, Gainesville, FL, 32611-7800, USA
2 - University of Florida, Department of Biology, 220 Bartram Hall, P.O. Box 118526, Gainesville, FL, 32611, USA
Presentation Type: Oral Paper:Papers for BSA Sections
Location: Cottonwood D/Snowbird Center
Date: Tuesday, July 28th, 2009
Time: 5:00 PM