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Genetic diversity in Chihuahuan Desert populations of creosotebush (Zygophyllaceae: Larrea tridentata )
Author(s) -
Duran Kristy L.,
Lowrey Timothy K.,
Parmenter Robert R.,
Lewis Paul O.
Publication year - 2005
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.3732/ajb.92.4.722
Subject(s) - larrea , biology , inbreeding , genetic variation , population , range (aeronautics) , zygophyllaceae , ecology , genetic diversity , arid , shrub , botany , genetics , demography , materials science , sociology , gene , composite material
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.