Molecular Ecology and Evolution
Moore, Michael , Douglas, Norman , Hernández-Ledesma, Patricia , Taylor, Sarah J. , Charboneau, Joseph , Brunner, Anna , Sanders, Jeffrey C. , Levin, Jonathan , Lunde, Katarina , Kates, Heather-Rose , Weinmann, Sophia , Bruenn, Riva , Croley, Matthew , Plumb, Rachel , Canning, Christopher , Hampilos, Katherine , Sharninghausen, Liam , Schultz, Darrin .
A preliminary comparative study of the phylogenetics and phylogeography of Chihuahuan Desert gypsophiles: evidence for long-term community stability?
The Chihuahuan Desert can be likened to a sea of limestone dotted throughout by islands of gypsum (hydrated calcium sulfate). The hard surface crust and low nutrient content of gypsum substrates create serious difficulties for plant germination and establishment. Nevertheless, in the Chihuahuan Desert at least 200 plant species are endemic to gypsum (“gypsophilic”). Evidence from morphology, biogeography, and a few phylogenetic studies suggests that the Chihuahuan gypsophilic flora is relatively old, perhaps dating to the late Miocene (5-7 million years ago). Several genera of Chihuahuan plants contain multiple gypsophilic species that share distinct morphology, suggesting they form clades. Most of these gypsophilic taxa occur widely on gypsum across the Chihuahuan Desert despite the isolated, island-like nature of gypsum deposits. Moreover, pollen core evidence and our own preliminary phylogeographic studies suggest that the floristic composition of Chihuahuan Desert gypsum habitats may have remained relatively stable, even as woodlands replaced arid habitats during full-glacial episodes of the Pleistocene. We are comparing the phylogeny and phylogeography of 10 diverse and widespread gypsophilic plant groups in the Chihuahuan Desert, including Nerisyrenia (Brassicaceae), Acleisanthes and Anulocaulis (Nyctaginaceae), Dicranocarpus, Gaillardia, and subtribe Flaveriinae (Asteraceae), Oenothera sect. Calylophus (Onagraceae), Mentzelia (Loasaceae), Nama (Boraginales), and Sporobolus nealleyi (Poaceae), to test the hypothesis of long-term persistence of gypsophilic communities. Specifically, we predict that (1) gypsophilic taxa within each of our target groups form clades that predate the Pleistocene, (2) genetic diversity within species is strongly partitioned geographically, reflecting limited gene flow among individual isolated gypsum deposits, and (3) in contrast to most phylogeographic studies of temperate plants, we will not see patterns that show evidence of Holocene dispersal from Pleistocene refugia. Here we present preliminary phylogenetic and phylogeographic results for several of these groups, including comprehensive phylogenies of Anulocaulis, Acleisanthes, HaploÃ«sthes, and Sartwellia. We also present evidence of significant geographically correlated sequence variation within several widespread gypsophilic taxa including Anulocaulis leiosolenus, Nerisyrenia linearifolia, and Sartwellia flaveriae.
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1 - Oberlin College, Biology Department, 119 Woodland Street, Science Center K111, Oberlin, Ohio, 44074-1097, USA
2 - North Carolina State University, Department of Plant Biology, Campus Box 7612, Raleigh, NC, 27695, USA
3 - Universidad Nacional Autónoma de México, Depto. de Botánica, Instituto de Biología, Apdo. Postal 70-367, México, D.F., 04510, México
4 - University of Texas Austin, Section of Integrative Biology, 1 University Station, A6700, Austin, Texas, 78712-7640, USA
5 - Oberlin College, Biology Department, Science Center K123, 119 Woodland Street, Oberlin, OH, 44074, U.S.A
6 - Oberlin College, Biology Department, 119 Woodland St., Oberlin, OH, 44074, USA
7 - Oberlin College, Biology Department, 119 Woodland St., Science Center K123, Oberlin, OH, 44074, USA
8 - Oberlin College, Biology Department, 119 Woodland Street, Science Center K123, Oberlin, OH, 44074, USA
9 - Oberlin College, Biology Department, 119 Woodland St., Science Center, K123, Oberlin, OH, 44074
Presentation Type: Oral Paper:Papers for Topics
Location: 552A/Convention Center
Date: Wednesday, August 4th, 2010
Time: 8:00 AM