Sanders, Jeffrey C. , Moore, Michael .
The origins and biogeography of gypsophily in Oenothera sect. Calylophus (Onagraceae).
The Chihuahuan Desert flora contains a large and diverse array of species endemic to gypsum. Many of these gypsophilic taxa are geographically widespread, despite the island-like distribution of gypsum outcrops in the Chihuahuan Desert. Some morphological and phylogeographic evidence suggests that these widespread gypsophiles may be relatively old. As part of a larger effort to understand the origins and phylogeography of gypsophily in the Chihuahuan Desert, we have initiated a phylogenetic and phylogeographic study of Oenothera L. sect. Calylophus (Spach) W.L.Wagner & Hoch (Onagraceae). Sect. Calylophus forms a clade of 6 species and 9 subspecies that are native to arid and semi-arid habitats in central and southwestern North America. Members of the section usually grow on calcareous substrates, with two taxa either completely or essentially restricted to gypseous substrates in the Chihuahuan Desert region: the widespread Oenothera hartwegii Benth. subsp. filifolia (Eastw.) W.L.Wagner & Hoch, and an undescribed locally endemic taxon in subsect. Calylophus. We reconstructed a near-complete species-level phylogeny of sect. Calylophus to address the following questions: (1) What are the closest relatives of the gypsophilic taxa in the section?; (2) Does O. hartwegii subsp. filifolia form a genetically distinct taxon, or is there evidence of introgression with other taxa in the section?; and (3) Does subsp. filifolia possess geographically-correlated genetic variation, as has been documented in other widespread Chihuahuan Desert gypsophiles? We sampled 5 of the 6 species and most subspecies. Multiple populations were sampled for most taxa, including 17 populations of subsp. filifolia from across New Mexico and west Texas. We generated DNA sequence data for 5 chloroplast spacer regions (trnQ/rps16, ndhF/rpl32, rpl32/trnL, trnV/ndhC, and petA/psbJ). We present a phylogeny of the section based on combined results for all five spacer regions. Preliminary analyses detected intraspecific variation within subsp. filifolia that may be correlated with geography.
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Origins and Biogeography of Gypsophily in the Chihuahuan Desert
1 - Oberlin College, Biology Department, 119 Woodland St., Oberlin, OH, 44074, USA
2 - Oberlin College, Biology Department, 119 Woodland Street, Science Center K111, Oberlin, Ohio, 44074-1097, USA
Oenothera sect. Calylophus
plastid spacer regions.
Presentation Type: Poster:Posters for BSA Sections
Location: Event Tent/Cliff Lodge
Date: Monday, July 27th, 2009
Time: 5:30 PM