Master's Theses

Document Type

Thesis

Date of Award

Summer 2016

Degree Name

Master of Science (MS)

Department

Biology

Advisor

Dr. Brian Maricle

Abstract

Andropogon gerardii Vitman (big bluestem) is one of the most dominant and widely distributed grasses of the North American prairie. It is widely used in restoration projects for the recovery of grassland ecosystems. A. gerardii demonstrates genetic and adaptive variation among populations across the prairie. With the objective to understand the evolutionary relationship between the A. gerardii populations, two noncoding chloroplast DNA (cpDNA) spacers (rpl32-trnL(UAG) and trnQ(UUG)-rps16) were studied. Similarly, genetic differentiation among the populations was also calculated based on the spacers. The trnQ(UUG)-rps16 spacer had more polymorphic sites than the rpl32-trnL(UAG) spacer. A phylogenetic tree based on combined cpDNA spacers generated a monophyletic tree for A. gerardii with a Colorado population and sand bluestem (Andropogon hallii) as the outgroups. The monophyletic tree was further resolved into two sub-clades. Most of the branches and nodes were well supported, with more than 70% of posterior probability values. However, the grouping of populations did not support the resolution of the phylogenetic tree with geological distribution. Analysis of molecular variance suggests there is a low level of genetic differentiation among the populations, with 90% of variation within the populations and 10% of variation among the populations. The observed high genetic variation within populations could be the result of potential gene flow, polyploidy, and the outcrossing nature of big bluestem.

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Rights

© 2016 Tej Man Tamang

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