Horning, Matthew , Cronn, RC .
Preliminary range-wide characterization of chloroplast and nuclear genetic diversity in Purshia tridentata (Pursh.).
Antelope bitterbrush (Purshia tridentata Pursh DC; Rosaceae) is an arid-land shrub having a widespread distribution across much of the western United States and southern British Columbia, Canada. This long-lived species occupies an important ecological niche across a large elevation gradient (60-3,150m) in fire-dominated communities such as Ponderosa pine (Pinus ponderosa) forests, and Sagebrush (Artemesia sp.) and Juniper (Juniperus sp.) arid steppes. Because of its importance as a browse for large mammals and a food source for granivores, bitterbrush is a key rangeland restoration species and is frequently planted by Federal agencies following post-fire revegetation and restoration activities. We are examining genetic variation at quantitative traits and molecular markers to gain an understanding of the pattern of neutral and potentially adaptive genetic variation within this species; this information will be used to delimit plant movement guidelines. Here we report results from an initial screen of chloroplast and nuclear microsatellite loci and provide a baseline, range-wide assessment of neutral genetic diversity in bitterbrush. A preliminary survey of a subset of four chloroplast microsatellites revealed 14 unique cytotypes in 42 populations that span a geographic range of ~ 510,000km2. Total haplotypic diversity was high (hT=0.78) while within population diversity was relatively low (hS=0.14). These findings suggest a relatively limited seed dispersal mechanism of bitterbrush that is facilitated through the seed cashing activities of rodents. Preliminary results obtained from 8 highly polymorphic nuclear microsatellite loci will also be presented as a contrast to uniparentally inherited cpDNA, and to provide additional insight into the amount and apportionment of genetic diversity in bitterbrush.
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1 - USDA Forest Service, Forest Genetics, Pacific Nothwest Research Station, 3200 SW Jefferson Way, Corvallis, Oregon, 97331, USA
Presentation Type: Oral Paper:Papers for Topics
Location: Williford A/Hilton
Date: Tuesday, July 10th, 2007
Time: 4:30 PM