Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 9/25/2007
Publication Date: 9/27/2007
Citation: Zalapa, J.E., Brunet, J., Guries, R.P. 2007. Hybridization and introgression patterns between native red elm (Ulmus rubra Muhl.) and exotic, invasive Siberian elm (Ulmus pumila L.) examined using species-specific microsatellite markers [abstract]. CONGEN3: The Third International Conservation Genetics Symposium. p. 20.
Technical Abstract: Ulmus pumila (Siberian elm) is an invasive elm species, non-native to the United States, which hybridizes with Ulmus rubra (red elm), a U.S. native. While Siberian elm is highly tolerant to Dutch elm disease (DED), red elm populations in North America have been decimated by DED. In order to study the population genetic structure of each species and the genetic hybridization patterns between the two species, we developed 38 primer pairs for microsatellite loci in U. rubra and tested their cross-amplification in U. pumila original accessions from China housed at the University of Wisconsin-Madison Elm Arboretum. In addition, eleven primer pairs previously developed in U. laevis and U. carpinifolia (syn. U. minor) were tested for cross-amplification. Sixteen primers amplified in both species, and thirteen loci proved polymorphic (2 to 19 alleles per locus) in each U. pumila and U. rubra. Eight loci possessed species-specific alleles that unambiguously allowed the discrimination between U. pumila and U. rubra. In total 55 alleles specific to U. rubra and 26 specific to U. pumila were identified. First, we examined the genetic composition of 5 U. rubra populations (n = 100) and 53 U. pumila accessions original from China. Despite severe losses due to DED, higher genetic variability was observed for U. rubra than for U. pumila (DED tolerant). Second, we determined the genetic basis of 6 Wisconsin populations (n = 96) containing U. pumila and U. rubra and intermediate phenotypes (i.e., putative hybrids). Of the 96 putative hybrid tress sampled, fifty individuals were confirmed as hybrids, 31 proved to be U. pumila, and nine were identified as U. rubra genotypes. Using introgression and genetic diversity patterns of the hybrid swarms and parental species, we aim to determine whether U. rubra is being assimilated genetically by DED-tolerant, U. pumila via this hybridization process.