Thesis (M.S.) in Marine Biology--University of Maine, 2004. / Includes vita. Includes bibliographical references (leaves 70-79).

Seven single nucleotide polymorphisms in six genes (LEP, IGF2, MC1R, PMCH, CAPN1, and CAST) which had been shown to affect traits of economic importance were used to compare the allele frequencies and diversity of a Canadian population of Angus cattle and an International population. Genetic diversity was also measured using 22 microsatellite markers that were assumed not to be affected by selection.<p> The Canadian population consisted of 107 cows and 57 bulls, while the Canadian Angus Associations International Embryo Program population consisted of 26 calves. Black and red animals were represented in each population. Although the bulls of the Canadian population represent Angus from 16-17 years ago, and the cows of the Canadian population represent Angus from 2006-2007, no difference was observed in either the set of microsatellite genotypes nor the SNP genotypes.<p> A significant difference was found between the Canadian and International populations at CAST, with the Canadian population exhibiting a higher frequency of the favorable A allele than the International population. This allele is positively correlated with tenderness. No significant differences were found for the other genes. Both populations were in Hardy Weinburg equilibrium for all genes except MC1R, which affects coat color.<p> Using microsatellites, the total genetic variability of the two Angus populations was measured, showing that 93% of total variability was attributed to differences within, and not between, populations. Randomly chosen cattle could also be assigned to the correct population 97% of the time, based on microsatellite genotypes, and 75% of the time based on SNP genotypes.<p> Mean heterozygosity was 0.578 based on microsatellites and 0.332 based on SNPs. The proportion of genetic variability between the two populations was 3% based on microsatellites and 7% based on SNPs. It is possible this reflects the results of indirect selection differences in various countries.<p> Finally, Neis genetic distance was measured between the Canadian and International populations. The Canadian and International populations had a pairwise genetic distance of 0.097. In comparison, the genetic distance of Canadian Angus was 0.135 to Blonde dAquitaine, 0.251 to Simmental, 0.258 to Gelbvieh, 0.281 to Limousin, 0.305 to Holstein, 0.334 to Belgian Blue, and 0.452 to Hereford based on microsatellite markers.<p> The results of this study show that the Angus breed contains as much or more genetic diversity than other cattle breeds. Greatest genetic differences exist between individual animals, not between populations of cattle in Canada and other countries.

Thirteen New World populations of Megachile rotundata and M. apicalis and two Old World populations of M. rotundata were analyzed at 23 enzyme loci using cellulose acetate electrophoresis. Conventional and G- or C-banded karyotypes were also examined in these populations. The principal findings are (1) No differences were found in the level of heterozygosity between haplodiploid Megachile and that of other diploid insects. This is the first record showing the mean heterozygosity in the hymenopteran genus to be consistent with the mean of most other diploid insects. (2) There was no difference in the level of heterozygosity nor the percent polymorphic loci between males and females, and heterozygotes was discovered in males of the two megachilid species studied. (3) The heterozygosity levels among New World populations of M. rotundata and M. apicalis were similar, but both were more than twice that of Old World rotundata analyzed. This is consistent with the expectations of the founder-event models of both Carson and Templeton. (4) FST, the amount of genetic differentiation among populations, was greater among New World populations of apicalis sampled than among those of rotundata. The extensive commercialization in rotundata may have tempered interpopulation differences which might had occurred had the species been undisturbed. (5) Wrights "isolation by distance" model is inapplicable to either of the two Megachile species. In rotundata, the high gene flow level suggests that human commercial action may effectively disrupt any opportunity for the development of locally adapted populations through selection. In apicalis, little gene flow is present among the populations which is expected by both Carson and Templeton models. The absence of any clinal pattern in apicalis probably better reflects Templeton's transilience model. We believe that the random alteration of major alleles, implicit in transilience, more readily accounts for the distinct local populations we found in apicalis. (6) Chromosomal data suggest that both pericentric inversions and deletions have been involved in karyotype evolution of the two species and a primitive karyotype is proposed based on its ubiquitousness in all populations of both species. / Graduation date: 1993

Seven single nucleotide polymorphisms in six genes (LEP, IGF2, MC1R, PMCH, CAPN1, and CAST) which had been shown to affect traits of economic importance were used to compare the allele frequencies and diversity of a Canadian population of Angus cattle and an International population. Genetic diversity was also measured using 22 microsatellite markers that were assumed not to be affected by selection.<p> The Canadian population consisted of 107 cows and 57 bulls, while the Canadian Angus Associations International Embryo Program population consisted of 26 calves. Black and red animals were represented in each population. Although the bulls of the Canadian population represent Angus from 16-17 years ago, and the cows of the Canadian population represent Angus from 2006-2007, no difference was observed in either the set of microsatellite genotypes nor the SNP genotypes.<p> A significant difference was found between the Canadian and International populations at CAST, with the Canadian population exhibiting a higher frequency of the favorable A allele than the International population. This allele is positively correlated with tenderness. No significant differences were found for the other genes. Both populations were in Hardy Weinburg equilibrium for all genes except MC1R, which affects coat color.<p> Using microsatellites, the total genetic variability of the two Angus populations was measured, showing that 93% of total variability was attributed to differences within, and not between, populations. Randomly chosen cattle could also be assigned to the correct population 97% of the time, based on microsatellite genotypes, and 75% of the time based on SNP genotypes.<p> Mean heterozygosity was 0.578 based on microsatellites and 0.332 based on SNPs. The proportion of genetic variability between the two populations was 3% based on microsatellites and 7% based on SNPs. It is possible this reflects the results of indirect selection differences in various countries.<p> Finally, Neis genetic distance was measured between the Canadian and International populations. The Canadian and International populations had a pairwise genetic distance of 0.097. In comparison, the genetic distance of Canadian Angus was 0.135 to Blonde dAquitaine, 0.251 to Simmental, 0.258 to Gelbvieh, 0.281 to Limousin, 0.305 to Holstein, 0.334 to Belgian Blue, and 0.452 to Hereford based on microsatellite markers.<p> The results of this study show that the Angus breed contains as much or more genetic diversity than other cattle breeds. Greatest genetic differences exist between individual animals, not between populations of cattle in Canada and other countries.

Dark (Microdipodops megacephalus) and pallid (Microdipodops pallidus) kangaroo mice are ecological specialists found in arid regions of the Great Basin Desert of the southwestern United States. Historical and current habitat alterations have resulted in disjunct distributions and severely diminished abundance of both species. Phylogenetic and phylogeographic research has discovered unique mitochondrial clades within M. megacephalus (eastern, central, western, and Idaho clades) and M. pallidus (eastern and western clades). Population-genetic analyses targeting the same mitochondrial markers also have found low amounts of maternal gene flow among the clades. However, little is known about population structure and genetic demography (historical and current migration rates, historical and current effective population sizes) within each mitochondrial clade. Herein, nuclear-encoded microsatellite loci were isolated to evaluate the underlying processes that may have molded kangaroo mouse relationships and distributions. Results from population-genetic analyses support previous findings that there are at least three genetically distinct clades within M. megacephalus and two such clades within M. pallidus. Three clades of M. megacephalus appear to have undergone different demographic histories, with little to no migration among clades. The two clades of M. pallidus also appear to have experienced varying demographic change although there has been small but recent migration between them. Additionally, the contemporary effective population sizes of all clades within Microdipodops appear to be low, suggesting that these populations may have difficulty coping with environmental pressures and hence are at risk of extinction. Results of this study are consistent with the recommendation that each Microdipodops clade should be managed as separate units and continually monitored in an effort to conserve these highly specialized taxa.

Diss. (sammanfattning) Uppsala : Uppsala universitet, 2009. / Härtill 5 uppsatser.

Thesis (Ph. D.)--University of Washington, 2001. / Vita. Includes bibliographical references (p. 165-179).

published_or_final_version / Medicine / Master / Master of Philosophy

No description available.

Thesis (Ph.D)--University of Wollongong, 2004. / Typescript. Includes bibliographical references: leaf 163-173.