Abstract Detail
Systematics/Phytogeography / Taxonomie/ Section Zacharias, Elizabeth H. [1], Baldwin, Bruce G. [2]. Patterns and timing of diversification in American Atriplex (Chenopodiaceae). A phylogenetic investigation of American Atripliceae with expanded taxonomic sampling of C4 American Atriplex was carried out to examine phylogenetic relationships among the American C4 species and to estimate divergence times of major events within the American Atripliceae (e.g., the origin of C4 photosynthesis in Atriplex) using data from nuclear ribosomal DNA internal and external transcribed spacers and chloroplast DNA sequences. Results based on the expanded taxonomic sampling corroborate our previous finding that only one shift from C3 to C4 photosynthesis is required to explain photosynthetic pathway evolution in sampled lineages of New World Atripliceae according to both nrDNA and cpDNA. Both the C3 and C4 lineages of North American Atripliceae support Raven and Axelrod’s hypothesis of migration into the California Floristic Province (CaFP) by ancestors from the intermountain west of North America based on parsimony-based optimization of biogeographic history. Endemic CaFP Atriplex may have descended from at least two introductions of North American taxa into the CaFP. Woody species from western North America do not form a monophyletic group; woodiness has evolved numerous times within American Atriplex.
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1 - Harvard University Herbaria, Organismal and Evolutionary Biology, 22 Divinity Avenue, Cambridge, Massachusetts, 02138, USA
2 - University of California, Berkeley, Department of Integrative Biology, University and Jepson Herbaria, 1001 Valley Life Sciences Bldg. #2465, Berkeley, California, 94720, USA
Keywords:
C4 photosynthesis
Atriplex
Biogeography
Chenopodiaceae
California Floristic Province.
Presentation Type: Oral Paper:Papers for Sections
Session: 6
Location: Room 1/Woodward
Date: Monday, July 28th, 2008
Time: 9:30 AM
Number: 6007
Abstract ID:337 | 
