Electronic Theses and Dissertations

Identifier

667

Meeyoon Choo

Date

2012

Document Type

Thesis

Degree Name

Master of Science

Major

Biology

Committee Chair

Takuya Nakazato

Committee Member

Randall Bayer

Committee Member

Troy Wood

Abstract

Stipa hymenoides and Sphaeralcea parvifolia are native to rangelands in western North America and have been selected as priority species for the restoration of degraded grasslands in the Colorado Plateau. To study the natural population structure of these species, individuals were collected from 44 populations of Stipa hymenoides and 23 populations of Sphaeralcea (22 populations of S. parvifolia and one population of S. grossulariifolia) distributed throughout southwest U.S. including Arches and Canyonlands National Parks in Utah. Amplified fragment length polymorphisms (AFLPs) were used to assess the genetic diversity and population genetic structure of both species. Moderate levels of genetic differentiation were observed among populations in Stipa and Sphaeralcea (FST = 0.15 and 0.13, respectively; AMOVA between-population variance = 20% and 16%, respectively). There was significant genetic structure in Stipa with two distinct clusters falling roughly one either side of the Colorado River, which appears to act as a barrier to gene flow. Sphaeralcea, on the other hand, showed no genetic structure as the allelels were more or less randomly distributed across the sampled area. There was a significantly positive correlation between pairwise geographic and genetic distances among the populations of Stipa (r = 0.203, P < 0.05), suggesting the existence of Isolation by Distance (IBD), whereas there was a non-significant, negative correlation in Sphaeralcea (r = -0.0176, P > 0.05). These results suggest that Stipa, which is highly autogamous, has migrated according to the stepping-stone model, whereas the migration mode of Sphaeralcea, which is heterogamous and entomophilous, does not follow such a model, perhaps dispersing via long-distance seed and pollen movement.

Comments

Data is provided by the student.

Library Comment

Dissertation or thesis originally submitted to the local University of Memphis Electronic Theses & dissertation (ETD) Repository.

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