Bruenn, Riva , Brunner, Anna , Hernández-Ledesma, Patricia , Douglas, Norman , Moore, Michael .
A comprehensive phylogeny of Anulocaulis and its implications for the evolution of Chihuahuan Desert gypsophily.
Anulocaulis (Nyctaginaceae) consists of five species, two of which are gypsophilic, or endemic to gypsum [A. reflexus I. M. Johnst. and all four varieties of A. leiosolenus (Torr.) Standl.: vars. leiosolenus, howardii Spellenberg & T. Wootten, lasianthus I.M. Johnst. and gypsogenus (Waterf.) Spellenb. & T. Wootten]. Although Anulocaulis ranges throughout southwestern North America, it has a Chihuahuan Desert center of diversity. As a first step toward understanding the phylogeography of gypsophily within Anulocaulis, we reconstructed the phylogeny of the genus to address the following questions: (1) Has gypsophily evolved repeatedly, or does a single origin best explain the modern pattern of gypsophily in the genus?; (2) Is the current distribution of gypsophilic taxa within the genus best described by a relictual pattern or by dispersal following initial colonization of gypsum?; and (3) Do geographically isolated conspecific populations of Anulocaulis, particularly A. leiosolenus, display evidence of interpopulational sequence divergence, suggesting genetic isolation? To address these questions we reconstructed the phylogeny of the genus using 5 chloroplast spacer regions (ndhF/rpl32, rpl32/trnL, ndhC/trnV, rps16/trnQ, and petA/psbJ) and ITS for all taxa in the genus and several outgroups. Multiple populations of nearly all taxa within Anulocaulis were included. The two gypsophilic species form a strongly supported clade, with A. reflexus and A. leiosolenus vars. lasianthus and gypsogenus forming individual subclades. In contrast, the widely distributed var. leiosolenus was not monophyletic, although populations of this variety were strongly partitioned geographically, with populations in Nevada, Arizona, and Texas/New Mexico forming distinct groups. Our results suggest that geographically discrete populations have been separated for some time. The implications of the phylogeographic variation within A. leiosolenus for the evolution of gypsophily are discussed.
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1 - Oberlin College, Biology Department, 119 Woodland street, Science Center K 123, Oberlin, OH, 44074, USA
2 - Oberlin College, Biology Department, 119 Woodland Street, Science Center K111, Oberlin, Ohio, 44074-1097, USA
3 - Universidad Nacional Autónoma de México, Depto. de Botánica, Instituto de Biología, Apdo. Postal 70-367, México, D.F., 04510, México
4 - North Carolina State University, Department of Plant Biology, Campus Box 7612, Raleigh, NC, 27695, USA
Presentation Type: Poster:Posters for Sections
Location: Hall A/Convention Center
Date: Monday, August 2nd, 2010
Time: 5:30 PM