Lawrence, Travis , Datwyler, Shannon .
Testing the hypothesis of allopolyploidy in the origin of Penstemon azureus (Plantaginaceae).
Polyploidy has played a significant role in the evolutionary history of many groups of plants, but the phylogenetic relationships among polyploid species remains difficult to untangle because of both incomplete lineage sorting and reticulate evolution in allopolyploid species. Penstemon sect. Saccanthera (Plantaginaceae) contains 24 species of which four are documented as polyploids (4X, 6X, and 8X). The purpose of this study is to test the hypothesis of an allopolyploid origin of P.azureus, a hexaploid species. Previous studies have suggested that P.azureus is an allopolyploid derivative of P. parvulus (4X) and P.laetus (2X). Multiple accessions from across the geographic ranges of P.azureus, and six closely related species (P. laetus [2X], P. filiformis[2X], P. heterophyllus [2X, 4x], P. parvulus [4x], and P. neotericus [8x]), are being sequenced for three chloroplast intergenic spacer regions (rpl32-trnL, trnD-trnT,rpoB-trnC) and two nuclear loci (Adh and NIA). In total, 15 accessions are represented in the analysis. Parsimony and Bayesian analyses of the combined cpDNA dataset indicate that species-level patterns are not apparent within the species complex. However, the cpDNA data show a pattern consistent with the geographic localities of collections, suggesting extensive hybridization and introgression within the species complex. Parsimony and Bayesian reconstruction of the individual nuclear datasets were subjected to network analysis using the program PADRE. The preliminary Adh analysis supports P.heterophyllus (2X, 4X), P. laetus(2X), and P. parvulus (4X), as possible progenitors of P. azureus. Additional taxon sampling and further analysis of the NIA dataset will provide additional evidence and support for potential progenitors of P. azureus.
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1 - CSU Sacramento, Biological Sciences, 6000 J Street, Sacramento, CA, 95819-6077, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Delaware D/Hyatt
Date: Wednesday, July 11th, 2012
Time: 11:15 AM