Genetic diversity in Chihuahuan Desert populations of creosotebush (Zygophyllaceae:Larrea tridentata)

Abstract

We examined isozyme variation in the dominant Chihuahuan Desert shrub, Larrea tridentata (creosotebush), to determine the genetic variation within and among populations, the biogeographic relationships of populations, and the potential inbreeding in the species. We surveyed 17 populations consisting of 20 to 50 individuals per population along a 1600-km north-south transect across the Chihuahuan Desert. The southernmost population was near Villa Hidalgo, Mexico, and the northernmost near Isleta Pueblo, New Mexico. All 12 isozyme loci examined were polymorphic (H(t) = 0.416), with up to nine alleles per locus. Despite high levels of variation, we detected moderate inbreeding in L. tridentata populations. Most variation was found within rather than among populations (G(ST) = 0.118). Furthermore, recently established populations in the northern limits of the Chihuahuan Desert did not show decreased levels of genetic variation (H(o) = 0.336). A significant correlation was found between pairwise genetic and geographic distances (r = 0.305). Larrea tridentata showed and continues to show a massive range expansion into the arid and semi-arid regions of the American Southwest, but as shown by the high genetic variation, this expansion took place as a wave, rather than a series of founder events.

New insights on the origin of the woody flora of the Chihuahuan Desert: The case of Lindleya

“…For example, Agave lechuguilla has no geographic pattern, and differences have been attributed to the abundance of pollinators as correlated with latitude (Silva‐Montellano and Eguiarte, 2003). And in Larrea tridentata , a remarkable and abundant shrub in the Chihuahuan Desert, genetic variation was uniform and furthermore, in the northern limits of this desert, recently established populations did not show decreased levels of genetic variation (Duran et al, 2005).…”

“…Melampodium leucanthum populations responded to Quaternary climate oscillations in a cyclic manner, with autotetraploids originating multiple times but not forming genetically cohesive groups (Rebernig et al, 2010a, b). Remarkably, in the creosote bush, Larrea tridentata , a massive range expansion took place as a wave, rather than a series of founder effects (Duran et al, 2005). Its expansion has extended to the Sonoran and Mohave deserts, carried out by tetraploids (Laport et al, 2012, 2013).…”

Hidden phylogeographic complexity in the Sierra Madre Oriental: the case of the Mexican tulip poppy Hunnemannia fumariifolia (Papaveraceae)

“…The same pattern of distribution is found in another desert plant, Agave lechuguilla , for which populations seem to have originated in the north and more recently to have colonized the south (Silva‐Montellano & Eguiarte, 2003). In contrast, for the creosote bush, Larrea tridentata , another desert plant, populations recently colonized the north from southern refugia (Duran et al. , 2005).…”

Volatile organic compound emissions from <i>Larrea tridentata</i> (creosotebush)

“…For example, creosotebush (Larrea tridentata) is often referred to in Sonora, Mexico as hediondilla, the "little stinker". By the Last Glacial Maximum, creosotebush already inhabited the southwestern United States (Duran et al, 2005). Over the last century, the area dominated by creosotebush in North America has increased, and is associated with coincident land degradation during that time (Grover and Musick, 1990).…”