Publication Date


Date of Final Oral Examination (Defense)


Type of Culminating Activity


Degree Title

Master of Science in Biology



Major Advisor

Stephen Novak, Ph.D.


James F. Smith, Ph.D.


René Sforza, Ph.D.


Understanding species’ distributions provides a comprehensive biogeographical framework with which to evaluate theoretical and applied ecological and evolutionary questions. To date, few studies have used amplified fragment length polymorphisms (AFLPs) to assess the biogeographical patterns of a broadly distributed grass species, and none that I have found used AFLPs to specifically study biogeographical patterns of an invasive annual grass in its native range. The overall objective of my study was to assess the biogeographic pattern of the invasive, self-pollinating, annual grass Taeniatherum caput-medusae subspecies asperum (medusahead) in its native range in Eurasia using AFLPs. Seventy populations of medusahead from 13 countries in Eurasia were analyzed in this study with 110 AFLP loci. The populations of medusahead analyzed in this study possessed low to moderate levels of range-wide genetic diversity, which was largely partitioned among populations (i.e., high levels of genetic structure). In addition, my results indicated that genetic diversity was distributed randomly across the species’ native range thus providing no support for the Central-Marginal hypothesis. These AFLP results are concordant with a previous study that analyzed the same populations of medusahead using allozymes, with the AFLP method employed in this study providing a finer scale assessment of genetic structure. Finally, these results for medusahead are consistent with results reported for another highly self-pollinating, annual grass species that is broadly distributed across much of Eurasia.