Systematics Section / ASPT
Zacharias, Elizabeth H. , Baldwin, Bruce G. .
Phylogenetic analysis of North American Atriplex (Amaranthaceae/Chenopodiaceae) using ITS sequence data.
A phylogenetic investigation of Atriplex (ca. 250 species; Amaranthaceae/Chenopodiaceae) is underway to examine evolutionary patterns, historical biogeography, life-form shifts, and ecophysiological change in the North American lineages (ca. 62 species), with an emphasis on Californian diversity (ca. 37 species, including eight endemics). The Californian taxa include annuals, perennial herbs, and shrubs and occur across a broad environmental spectrum, often in extreme environments, such as isolated salt or alkaline scalds; several taxa are regarded as rare or endangered and are taxonomically problematical. Recently published sequence-based phylogenetic work suggested that Atriplex sensu lato is a monophyletic genus, in contrast with published results of morphological cladistic analysis; weak support or limited taxon sampling in the previous analyses have left relationships within Atriplex insufficiently understood. Molecular phylogenetic analyses are being conducted to determine whether Atriplex , as traditionally recognized, and the North American taxa are each monophyletic groups and whether the current circumscription of the genus needs revision. Preliminary phylogenetic analyses show that ITS sequence data provide sufficient variation to allow considerable resolution of Atriplex phylogeny. The results suggest that life-form evolution in Atriplex has been dynamic, with multiple, independent shifts between perennial and annual habits in the North American taxa. Exploration of additional taxa and gene regions is being pursued to clarify further the evolutionary history of Atriplex and, more generally, to contribute to understanding of evolutionary changes associated with increasing aridity.
1 - University of California, Berkeley, Integrative Biology, University and Jepson Herbaria, 1001 Valley Life Sciences Building, Berkeley, California, 94720-2465, USA
nr DNA ITS
Presentation Type: Paper
Location: Cottonwood C (Snowbird Center)
Date: Wednesday, August 4th, 2004
Time: 2:30 PM