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Abstract Detail

Systematics Section/ASPT

Riser, James [1], Roalson, Eric [1].

Phylogenetic relationships among the North American Cleomoids (Cleomaceae): A test of Iltis' reduction series.

The Cleomoid clade (Cleomaceae) is a monophyletic group of mostly herbaceous annuals found predominately in western North America. Species circumscriptions have been relatively stable; however, generic relationships have been subject to considerable change. Currently, five genera are recognized(Carsonia, Cleomella, Oxystylis, Peritoma, and Wislizenia). Historic evolutionary hypotheses regarding generic relationships among the Cleomoids were based on morphological characters combined with the geographic distributions of the species. Using the nrDNA ITS and cpDNA psbA-trnH, rpl32-trnL, and trnQ-rps16 intergenic spacer regions, we test previous hypotheses regarding: 1) the monophyly of the five currently recognized genera; 2)evolution of fruits from larger, multi-seeded siliques to smaller, few-seeded schizocarps/nutlets; and 3) the transition of the raceme inflorescences from bracteate to ebracteate. The evolution of fruit size/type and the loss of bracts within the inflorescences have traditionally been interpreted within the context of adaptations to increasingly arid habitats. Our phylogenetic analyses indicate that not all of the currently recognized genera are monophyletic and the relationships between them may not be as straightforward as previously hypothesized. Additionally, evolution of fruit types and the loss ofinflorescence bracts may not represent a linear reduction correlated with increasing aridity.

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1 - Washington State University, School Of Biological Sciences, Abelson Hall 339, Pullman, WA, 99164-4236, USA


Presentation Type: Oral Paper:Papers for Sections
Session: 26
Location: Franklin B/Hyatt
Date: Tuesday, July 10th, 2012
Time: 10:15 AM
Number: 26009
Abstract ID:334

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