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Geyer, Renee [1], Everbach, Sophie [1], Douglas, Norman [2], Flores-Olvera, Hilda [3], Ochoterena, Helga [4], Moore, Michael [1].

Phylogeography of Petalonyx crenatus (Loasaceae): genetic structure across a gypsum archipelago.

Gypsum soil exposures are found throughout the Chihuahuan Desert Region of Mexico and the United States. Gypsum is a harsh soil for plants to grow on and yet numerous species grow only on gypsum exposures. Petalonyx crenatus is a gypsum endemic shrub that is found throughout western and central Coahuila, Mexico. During the full-glacial periods of the Pleistocene Epoch, this desert biome disappeared and was replaced by a cooler, wetter climate in which many desert plants could no longer survive. Our first hypothesis is that gypsum endemics survived full-glacial periods because of reduced competition from other plants since gypsum is a challenging soil for most plants. If this is correct, gypsum endemics that originated before the Pleistocene will have high genetic diversity across their geographic ranges. Our second hypothesis is that gypsum endemics are dispersal limited like island endemics because gypsum outcrops function as gypsum “islands.” Gypsum endemics will have low gene flow between populations if this hypothesis is correct. The chloroplast ndhF-rpl32 and rpl32-trnL spacer regions and nuclear ITS were sequenced from 5-20 P. crenatus plants per population from different geographic locations across the geographic range of the species. A haplotype network and a maximum parsimony phylogeny were constructed from the chloroplast DNA and various population genetic parameters (Tajima’s D, Haplotype diversity, Nst, and Gst) were calculated. These statistics showed high variation between populations and low variation within each population supporting our hypothesis that P. crenatus is dispersal limited and persisted in western and central Coahuila through the Pleistocene.

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1 - Oberlin College, Department of Biology, 119 Woodland St, Oberlin , OH, 44074, USA
2 - University Of Florida, Biology, Bartram Hall, 876 Newell Dr, Gainesville, FL, 32611, United States
3 - Instituto de Biología, UNAM, Departamento de Botánica, Apartado Postal 70-233, Mexico City, 04510, México
4 - Instituto de Biología, UNAM, Departamento de Botánica, Apartado Postal 70-233, Mexico City, 04510, México

Chihuahuan Desert.

Presentation Type: Poster
Session: P1, Biogeography Posters
Location: Virtual/Virtual
Date: Monday, July 19th, 2021
Time: 5:00 PM(EDT)
Number: P1BG008
Abstract ID:528
Candidate for Awards:None

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