Download (PDF 958 KB): https://research.fs.usda.gov/download/treesearch/44436.pdf
Abstract
The long separation of the Chihuahuan and Sonoran Deserts is reflected in the high species richness and endemism of their floras. Although many endemic species from both deserts reach their distributional limits where the Sierra Madre Occidental massif fragments into smaller mountain complexes in northern Mexico and adjoining areas of the United States, indicator species approaches to identify the boundary between the Chihuahuan and Sonoran Deserts are complicated by differences in physiology and morphology among species that independently influence their local occurrences. Here we use an alternate approach that examines distributional differences within a single species that is widespread in both deserts. We find that diploid and tetraploid Larrea tridentata occur sympatrically at an abrupt boundary in the low elevation areas of the Gila and San Pedro Rivers of southeastern Arizona. This cytotype boundary is correlated with climatic and vegetational transition, is consistent with a boundary between the Chihuahuan and Sonoran Deserts first suggested by Shreve, and raises interesting questions about the historical persistence of this contact zone.
Parent Publication
Keywords
Madrean Archipelago,
Sky Islands,
southwestern United States,
northern Mexico,
natural environment,
fauna,
flora,
research,
management,
biodiversity,
climate change
Citation
Laport, Robert G.; Minckley, Robert L.. 2013. Cytogeography of Larrea tridentata at the Chihuahuan-Sonoran Desert ecotone. In: Gottfried, Gerald J.; Ffolliott, Peter F.; Gebow, Brooke S.; Eskew, Lane G.; Collins, Loa C. Merging science and management in a rapidly changing world: Biodiversity and management of the Madrean Archipelago III and 7th Conference on Research and Resource Management in the Southwestern Deserts; 2012 May 1-5; Tucson, AZ. Proceedings. RMRS-P-67. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. p. 218-224.
