Great Basin Naturalist


Species of Artemisia (subgenus Tridentatae) dominate much of western North America. The genetic variation that allows this broad ecological adaptation is facilitated by hybridization and polyploidization. Three separate studies were performed in this group using randomly amplified polymorphic DNA (RAPD). Fifty-seven 10-mer primers generated nearly 400 markers from genomic DNA obtained from leaf tissue. These studies were (1) a measure of the variability of plants within and between populations and between subspecies using 5 A. tridentata ssp. wyomingensis populations, 2 A. cana ssp. cana populations, and 1 A. cana ssp. viscidula population; (2) an examination of the hypothesis that tetraploid (4x) Artemisia tridentata spp. vaseyana derives de novo from diploid (2x) populations via antopolyploidy; and (3) an examination of the validity of the status of putative hybrids that have been produced by controlled pollination. These latter hybrid combinations—A. tridentata ssp. tridentata × A. t. ssp. vaseyana, A. t. ssp. wyomingensis × A. tripartita, and A. cana ssp. cana × A. tridentata ssp. wyomingensis—were made to combine traits of parental taxa in unique combinations with possible management application. RAPD marker data were subjected to similarity and UPGMA clustering analyses. RAPD markers were effective in measuring genetic diversity at different systematic levels. Individual plants within a population were approximately 55% to > 80% similar to one another; populations within subspecies gave corresponding values of similarity, probably a result of the combined effects of large population sizes and wind pollination. The 2 subspecies of A. cana were approximately 45% similar. At least some 4x populations of A. tridentata ssp. vaseyana apparently derive de novo from 2x plants based on their being embedded in 2x phenogram groups, thus reinforcing evidence that autopolyploidy plays an important role in Tridentatae population biology. Two (A. tridentata ssp. tridentata × A. t. ssp. vaseyana and A. cana ssp. cana × A. tridentata ssp. wyomingensis) of the 3 putative hybrid combinations were confirmed to include hybrids. These hybrids may have potential in management applications. Additional use of RAPD technology combined with other techniques may be useful in delimiting genetic characteristics and in guiding artificial selection in Tridentatae.