Abstract Detail



Biogeography

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

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

The Chihuahuan Desert region in Mexico contains isolated “island-like” deposits of exposed gypsum, a sulfur and calcium-rich soil that hosts a diverse endemic flora. Because most plant species do poorly on gypsum, these deposits tend to have lower overall plant cover and presumably lower overall competition. We hypothesize that adaption of gypsum endemics to gypsum has protected these taxa from community turnover during the Pleistocene. We also hypothesize that, based on paleoclimate evidence, central and western Coahuila have experienced the least amount of climate change in the Chihuahuan Desert region.  To test these hypotheses, we undertook a preliminary phylogeographic study of the gypsum endemic taxon Petalonyx crenatus (Loasaceae). These shrubs are endemic to gypsum exposures of central and southwestern Coahuila.  Samples from 4-6 individuals of the gypsum endemic Petalonyx crenatus were collected at 14 geographically isolated populations, and the ndhF-rpl32 and rpl32-trnL spacer regions were sequenced for all individuals. A maximum parsimony phylogeny and a haplotype network were estimated from the sequences. We found that 13 of the 14 populations were fixed for one plastid haplotype, and that haplotypes were not broadly shared among populations. This suggests that seed-mediated gene flow is limited and populations may have persisted in place through time. One population (Sierra del Yeso, southwestern Coahuila) had a highly distinctive haplotype in P. crenatus and may represent a cryptic taxon. Increased sample sizes among and within all populations are required to increase the statistical power of the results. However, our results for P. crenatus are very similar to phylogeographic studies of  gypsum endemic Fouquieria shrevei and Acleisanthes, which share similar distributions in Coahuila and similar habits, suggesting that gypsum plant communities may have been relatively stable throughout the Pleistocene in Coahuila.


Related Links:
The Origin and Evolution of Gypsum Endemic Plants


1 - Oberlin College, 119 Woodland St., Oberlin, OH, 44074, USA
2 - University Of Florida, Biology, PO Box 118525, Gainesville, FL, 32611, United States
3 - Instituto de BiologĂ­a, UNAM, Apartado Postal 70-367, Mexico, DF, 04510, Mexico
4 - Oberlin College, Department Of Biology, 119 Woodland St., Science Center K111, Oberlin, OH, 44074, United States

Keywords:
Petalonyx
Loasaceae
Phylogeography
gypsum
Chihuahuan Desert
Mexico.

Presentation Type: Poster
Number: PBG003
Abstract ID:513
Candidate for Awards:None


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