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Genetics Section

Novak, Stephen J. [1], Hansen, Kevin T. [2], Score, Matthew [2], Sforza, Rene [2].

Genetic variation in Taeniatherum caput-medusae (Poaceae): analysis of native range populations.

Taeniatherum caput-medusae is a primarily self-pollinating annual grass native to Eurasia. The species was introduced into western United States in the late 1800s, and is now widely distributed over semi-arid portions of California, Idaho, Nevada, Oregon, Utah and Washington. The objectives of this study were to identify source populations for the introduction of this grass into western U. S., and assess the genetic consequences of these introductions. Twenty-three native populations of T. caput-medusae from Greece, Turkey, Iran, Afghanistan, Tadzhikistan and Kazakhstan were included in this analysis. Allozyme diversity in these populations was determined by staining for 15 enzymes that were coded for by 29 loci. Across all Eurasian populations, we detected a total of seven polymorphic loci and 39 alleles, while five polymorphic loci and 34 alleles were detected in the western U.S. Four of 23 (17%) Eurasian populations were genetically polymorphic, while 16 of 45 (35.5%) introduced populations were polymorphic. On average, 0.75% of loci were polymorphic within native populations, whereas 1.76% of loci were polymorphic in introduced populations. Most of the allozyme diversity of Eurasian populations is partitioned among rather than within populations. These results of allozyme diversity for native and introduced populations of T. caput-medusae suggest that the grass did experience a genetic bottleneck (at the across-population level) as a consequence of its introduction into western U.S. However, multiple introductions of different genotypes appear to have contributed to higher levels of allozyme diversity, on average, within introduced populations. None of the native populations analyzed in this study possessed the multilocus genotypes detected in introduced populations. Thus, source populations (or regions) cannot be clearly identified, and the analysis of additional native populations, especially from Europe, will be required.


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1 - Department of Biology, Boise State University, 1910 University Drive, Boise, Idaho, 83725-1515, USA
2 - Department of Biology, Boise State University, 1910 University Dr., Boise, Idaho, 83725-1515, USA

Keywords:
genetic diversity
Invasive Species
medusahead
multiple introductions
Taeniatherum caput-medusae.

Presentation Type: Poster
Session: 33-50
Location: Salon C, D & E - Gov Ballroom/Hilton
Date: Tuesday, August 16th, 2005
Time: 12:30 PM
Abstract ID:505


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