Date of Award:

5-1-2000

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Biology

Committee Chair(s)

James A. MacMahon

Committee

James A. MacMahon

Committee

C. Anna Toline

Committee

W. Sue Fairbanks

Abstract

The use of reintroductions has become a widely used tool in the conservation of bighorn sheep (Ovis canadensis). In an effort to reestablish populations of bighorn sheep in Utah, 23 individuals from two existing populations in British Columbia, Canada, Tranquille and Harper Ranch, were transplanted to Antelope Island in the Great Salt Lake of Utah. The two British Columbian populations had been founded from a native population near William's Lake, also in British Columbia. Small transplanted populations may have lower levels of genetic variation relative to the source population due to the chance loss of alleles following the founder event. In addition, this variation may be further reduced through inbreeding and drift, which are increased as a consequence of small effective population size, Ne. RFLP (restriction fragment length polymorphism) analysis of the mitochondrial genome, as well as microsatellite and RAPD (randomly amplified polymorphic DNA) analysis of the nuclear genome were used to estimate molecular variation following these transplants. Mitochondrial variation was lost in the initial transplant from William's Lake to Tranquille and Harper Ranch. Three haplotypes were found in the initial population; no mitochondrial variation was found in subsequent populations. Number of polymorphic RAPD loci decreased with each founder event, ranging from 9.0% in the William's Lake population to 6.9% in the Antelope Island population. Levels of microsatellite heterozygosity did not decline with each transplant. Population differentiation was measured to determine if transplants had been representative of the source populations. Overall measures of population differentiation indicated little to moderate levels of population genetic structure (FST=0.045; ΦST=0.086). Number of polymorphic RAPD loci decreased in the F1 generation (3.2%) relative to the parental generation (6.9%) on Antelope Island most likely due to low effective population size. The estimate of effective population size from demographic data is 12.8. These data indicate that founder effect and low effective population size have resulted in reduced levels of genetic variation in these populations.

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