Putnam, Emily , Allphin, Loreen , Windham, M. D. .
An investigation of ecological and genetic variation among populations of Tahoe draba (Draba asterophora; Brassicaceae).
DRABA asterophora (Brassicaceae) is known from ~10-12 populations occupying a narrow range of alpine habitats near Lake Tahoe. These are partitioned into three population clusters located northeast, south, and southwest of the lake. The southwest population cluster has been segregated as variety macrocarpa, whereas the other two clusters have been assigned to variety asterophora. Because this small, matted, perennial occurs at alpine sites, the species faces impending threats to its habitat through ski run expansion and development. Because little information is available for this rare species, it is difficult to ascertain the impact of such ski run development on the long-term survival and persistence of the Tahoe draba. With funding from the USDA Forest Service and local ski resorts, we are conducting morphological, ecological, chromosomal, and genetic studies of D. asterophora (both varieties) to provide a framework upon which future management plans and mitigation can be developed. Preliminary results suggest that there are significant differences between the three population clusters. These include differences in soil composition, soil chemistry, plant density, demographics and reproductive success. Chromosome counts from the northeastern populations (Mt. Rose, Nevada) are tetraploid (n=20). Allozyme banding patterns support the hypothesis that these have arisen through autopolyploidy. Although diploid counts have not yet been obtained for D. asterophora, genetic studies suggest that diploids are present in some populations. Because the species includes more than one ploidy level, it should not be treated as a single panmictic taxon for purposes of conservation.
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1 - Brigham Young University, Department of Integrative Biology, 401 Widtsoe Building, Provo, Utah, 84602, USA
2 - University of Utah, Utah Museum of Natural History, 1390 E. President's Circle, Salt Lake City, Utah, 84112, USA
Presentation Type: Oral Paper:Papers for Topics
Date: Tuesday, August 1st, 2006
Time: 3:30 PM