Sequences from several species endemic to gypsum deposits in the Chihuahuan Desert

Botanists have long recognized that certain plant species occur only on unusual soil types. Termed "edaphic endemics", these plants are thought to have adapted to aspects of particular substrates and in the process lost the ability to compete successfully on more ordinary soils. The gypsum deposits and gypseous soils of the Chihuahuan Desert host possibly the largest and most diverse substrate endemic flora in North America, with at least 200 taxa in more than 30 plant families restricted to gypseous substrates throughout the Chihuahuan Desert. In contrast to other well-characterized substrate-endemic floras such as the serpentine flora of California and Oregon, the CDR gypsum flora has received only sporadic attention from botanists and is thus incompletely known. The purpose of this project is to use comparative phylogenetic and phylogeographic approaches to understand evolutionary dynamics within the CDR gypsum endemic flora, with a focus on 12 regionally dominant lineages. More specifically, the goals of the study include testing whether gypsum endemics first appeared in the CDR in the Miocene/Pliocene or later, whether regionally dominant gypsum endemics remained relatively widespread during Pleistocene full-glacial periods or were reduced to one or a few refugia, and whether the Pleistocene full-glacials promoted speciation in gypsum endemic lineages.