Thesis
Genetic variation in Bromus tectorum (L.) in the U.S. Southwest and California
Washington State University
Master of Science (MS), Washington State University
2011
Handle:
https://hdl.handle.net/2376/103666
Abstract
Genetic variation in the invasive grass Bromus tectorum (cheatgrass) has been extensively studied throughout much of its introduced range in North America and portions of its native range in Europe and Asia. Sixty populations of B. tectorum were collected throughout California and the Southwest United States and genetic variation was analyzed at 25 allozyme loci. The average number of alleles per locus (A) is 1.03, percent polymorphic loci (% P) is 3.27, and expected heterozygosity (Hexp) is 0.007. Total gene diversity (HT = 0.060) is lower than total gene diversity for populations in most other regions of North America and the native range. Most genetic variation is partitioned within populations rather than among populations (GST = 0.275), a pattern that has also been observed in the mid-continent U.S. and Western North America. The Got-4c multilocus genotype which is prominent in the Pacific Northwest and Western Canada also occurs throughout this region with its highest frequency in Northern California. In combination with herbarium records, this prominence supports the hypothesis that B. tectorum was first introduced into California from the Pacific Northwest, rather than along its coastline. Two novel multilocus genotypes (Pgi-2b & Got-4c, Tpi-1b & Got-4c) and one heterozygous individual appear in the California-Southwest U.S. region; the latter provides evidence of outcrossing in this highly selfing species. The distribution of multilocus genotypes throughout North America reinforces the contention that multiple introductions of B. tectorum have occurred.
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Details
- Title
- Genetic variation in Bromus tectorum (L.) in the U.S. Southwest and California
- Creators
- Angela Rose Pawlak
- Contributors
- Richard Norton Mack (Degree Supervisor)Stephen J. Novak (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Biological Sciences, School of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; Pullman, Wash. :
- Identifiers
- 99900524881501842
- Language
- English
- Resource Type
- Thesis