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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
161

Pollination Biology of the Endemic Erigeron lemmonii A. Gray, and its Insect Visitor Networks Compared to two Widespread Congeners Erigeron arisolius G.L. Nesom and Erigeron neomexicanus A. Gray (Asteraceae)

Bailey, Pamela 15 April 2013 (has links)
This thesis is an investigation of network analysis to understand differences between how three congeners have adapted pollination network strategies to ensure adequate gene flow. This study will focus on three species of Erigeron (Fleabanes), one endemic species adapted to cliff wall habitat in one canyon fragmented by topography (E. lemmonii) at Fort Huachuca Military Reserve, and two others (E. arisolius and E. neomexicanus) adapted to more diverse habitat conditions in a larger range in Arizona, USA. Sustainability of military lands and protected species are primary concerns for Army land management, and these findings will be made available to the U.S. Army, and U.S. Fish and Wildlife Service resource managers to use in their respective management plans. UCINET software was used to construct the insect flower visitor networks for the three Erigeron species by recording insect visitors / plant interactions and comparing their visitation networks to each other. Erigeron arisolius and E. neomexicanus have redudndant network architecture, compared to E. lemmonii which has a fragile network supporting a unique insect community. If the E. lemmonii population disappears, a collapse of its dependent insect visitors may also occur. Other new botanical information was discovered and recorded for E. lemmonii. It has a xenogamous mating system, and can also reproduce by vegetative means. An individual capitulum has a three week flowering period, and the population has individual plants blooming over a six month flowering season with May being the peak. It grows in highly organic soil on cliff face crevices in the Scheelite Canyon. Another aspect was to develop and publish genetic microsatellite markers for the three species of Erigeron, which are the first microsatellite markers to be identified for this genus. This included determining the chromosome number of E. lemmonii, before the genetic markers could be identified for this species. Eight microsatellite markers were identified for E. lemmonii and nine markers were identified for E. arisolius. However, no markers for E. neomexicanus were identified because of confounding results. Erigeron lemmonii has less genetic diversity, lower mean heterozygosity and fewer alleles, than E. arisolius. / This study was funded by the U.S. Army Environmental Quality Technology Program, at the U.S. Army Engineer Research and Development Center (Project 09-03).
162

Identification des bases évolutives de la diversité génétique des populations de naseux des rapides (Rhinichthys cataractae) dans l'est du Canada

Girard, Philippe January 2007 (has links)
Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal
163

Design, Test, Calibration and Qualification of Satellite Sun Sensors, Power Systems and Supporting Software Development

Gavigan, Patrick 30 May 2011 (has links)
This thesis describes technologies developed for nanosatellites at the Space Flight Laboratory. A critical ground station component, the Terminal Node Controller, was upgraded in order to support Generic Nanosatellite Bus and future missions. Sun sensor requirements and operation were reviewed, followed by details of the author's work in executing the acceptance testing on these parts, including thermal shock testing, thermal functional testing, calibration, system level testing and on orbit commissioning. A new calibration test process was developed, along with supporting structure and software to ease the testing process, producing accurate calibration parameters and expected performance results for the sensors. A thermal qualification campaign was completed, demonstrating that sun sensors are capable of functioning with negligible performance degradation after exposure to extreme temperatures. A process for installing the sun sensor pin hole was developed using photolithography. Finally, power subsystem analysis for the NEMO-AM mission is presented.
164

Landscape Genetics of the Marbled Salamander (Ambystoma Opacum) at Mammoth Cave National Park

Martin, James Kyle 01 December 2013 (has links)
Habitat connectivity is important to maintain in order to prevent loss of genetic diversity, reduce inbreeding depression, and decrease extinction risk in threatened or endangered species. Here I present a landscape genetics study on marbled salamanders (Ambystoma opacum) in highly connected forested habitat at Mammoth Cave National Park. This investigation of gene flow among ponds within a mostly continuous landscape provides data that can be compared with patterns observed in more fragmented landscapes. These comparisons can provide a means of investigating the separate effects of structural and functional habitat connectivity on amphibian genetic population structure. Structural connectivity refers to the pattern of available habitat, and functional connectivity refers to the organism’s response to the available habitat (i.e., use of alternative habitat types). Five hundred fifty-six individuals were sampled from 50 ponds and screened at eight microsatellite loci to look for genetic population structure. Structure did exist at the park, with the best predictor of breeding pond isolation being interpond distance. Wet deciduous forest appears to offer lower resistance to gene flow in this species than dry deciduous or coniferous forest habitat, while the Green River appears to serve as a partial barrier to gene flow. Overall, my data suggest that marbled salamanders at Mammoth Cave National Park frequently move among breeding ponds, and these individuals within these ponds experience extensive amounts of gene flow. This confirms that the seemingly continuous pattern of habitat at Mammoth Cave National Park has resulted in well-connected subpopulations that frequently share genetic material.
165

Colorectal Cancer : Aspects of Heredity, Prognosis and Tumour Markers

Ghanipour, Lana January 2014 (has links)
Colorectal cancer (CRC) is one of the most common cancer types and leading causes of cancer death worldwide. Since CRC is a heterogenic disease, there is a demand for increased knowledge of the underlying genetic and epigenetic mechanisms. The aim of this thesis was to investigate heredity and potential tumour markers in relation to prognosis. In paper I, survival of patients with CRC and a positive family history of CRC in first-degree relatives was analysed. Patients with colon cancer and positive family history of CRC had improved survival compared to patients with negative family history. This improvement in survival could not be explained by known clinico-pathological factors. In paper II, we investigated the prognostic value of Tryptophanyl t-RNA synthetase (TrpRS) in tissues from patients operated for CRC. Low protein expression of TrpRS in primary tumour tissues correlated with increased risk of recurrence and poorer survival. In paper III, the prognostic value of microsatellite instability (MSI) and the correlation to heredity for CRC in first-degree relatives was investigated. Patients with proximal colon cancer and MSI had improved cancer specific survival. There were no correlation between MSI and heredity. In paper IV, we evaluated the potential use of proximity ligation assay (SP-PLA) in patients with CRC, by simultaneous analysis of 35 proteins in only 5 μl plasma. SP-PLA is a suitable method for protein detection and might give valuable guidance in pursuing new prognostic and predictive tumour markers. However, none of the markers selected for present SP-PLA analyses gave better prognostic information than CEA. In conclusion, heredity is related to better survival independent of MSI in patients with CRC and MSI is associated with better prognosis in proximal colon cancer. Detection and increased knowledge of molecular mechanism in CRC is important, however it needs to be further investigated and validated in clinical use.
166

Conservation Genetics of Freshwater Turtles

Davy, Christina M. 19 March 2013 (has links)
Turtles have long life spans, overlapping generations and promiscuous mating systems. Thus, they are an ideal system with which to investigate the application of conservation genetics methods and assumptions to long-lived organisms. Turtles are also one of the most threatened groups of vertebrates and conservation genetics studies are essential to effective recovery of turtle species. This thesis has two main objectives: 1) to evaluate some common population genetics assumptions with respect to turtles and other long-lived organisms, and 2) to collect important information on the population genetics of threatened turtles in Ontario, which can be used to inform species recovery. In Chapters Two and Three, I describe the development of novel microsatellite markers for the snapping turtle and spiny softshell. In Chapter Four I demonstrate significant genetic structure in populations of the endangered spotted turtle in Ontario, and find that “bottleneck tests” may fail to detect recent population declines in small turtle populations. I also show that spotted turtles do not show the typical correlation between population size and genetic diversity. In Chapter Five I use microsatellite markers developed in Chapter Two and document population structure in the widespread snapping turtle for the first time. I compare these results with results from Chapter Four to test the traditionally accepted hypothesis that genetic diversity is reduced in small, isolated populations compared to large, connected populations. As in Chapter Four, my results suggest that the usual patterns of genetic structure and loss of diversity may not apply to turtles. In Chapter Six I conduct a conservation genetics study of the endangered Blanding’s turtle. Finally, in Chapter Seven I combine results from spotted, snapping and Blanding’s turtles to test whether vagility predicts population structure, genetic diversity and significant barriers to gene flow in three species sampled across a single landscape. Analyses reveal minimal congruence in barriers to gene flow and the three species show unexpected and contrasting patterns of diversity across the landscape. Discordant patterns among species highlight areas for further research and shed light on possible cryptic behaviour, and I discuss potential further directions for research in the Summary.
167

Morphometric, Mtdna And Microsatellite Analysis In Honeybee Populations (apis Mellifera L.) Of North And Northwest Iran

Jabbarifarhoud, Houman 01 September 2004 (has links) (PDF)
ABSTRACT MORPHOMETRIC, MtDNA AND MICROSATELLITE ANALYSIS IN HONEYBEE POPULATIONS (Apis mellifera L.) OF NORTH AND NORTHWEST IRAN Morphometric measurements, mitochondrial DNA analyses and 5 microsatellite loci were used to investigate variation in the honeybee populations of Iran and comparing it with the Turkish populations. Five honeybee populations were sampled from North and west north of Iran. In morphometric aspect of the study 23 characters were measured from left forewings and hindlegs of honey bee samples. The data were analysed by multivariate statistical analyses. By using mtDNA analyses length polymorphism of the intergenic region COI-COII of mitochondrial DNA was studied. After amplification of this region by the polymerase chain reaction, DraI enzyme was used for restriction of amplified region. Results of mtDNA studies show no diversity between four populations and all of them exhibit the same C1 pattern. Five microsatellite loci (A7, A24, A28, A43 and A113) were used in this studies.A high level of average heterozygosity changing between 0.611 and 0.709 was detected in Iranian honey bee populations, and a significant degree of polymorphism was observed. Although Urmia, Sarein and Viladereg populations are similar, Amol population which has located in northern Iran shows a significant difference from other populations. Result obtained form morphometric studies are supporting microsatellite analyses. By comparing data obtained form Iranian honey bee populations with Turkish population (Hakkari), western populations (Urmia, Sarein and Viladereg) are more similar to Hakkari population. It is found Amol is significantly different form other populations and better represents Iranian honeybee.
168

Genetic Structure Analysis Of Honeybee Populations Based On Microsatellites

Bodur, Cagri 01 September 2005 (has links) (PDF)
We analyzed the genetic structures of 11 honeybee (Apis mellifera) populations from T&uuml / rkiye and one population from Cyprus using 9 microsatellite loci. Average gene diversity levels were found to change between 0,542 and 0,681. Heterozygosity levels, mean number of alleles per population, presence of diagnostic alleles and pairwise FST values confirmed the mitochondrial DNA finding that Anatolian honeybees belong to north Mediterranean (C) lineage. We detected a very high level of genetic divergence among populations of T&uuml / rkiye and Cyprus based on pairwise FST levels (between 0,0 and 0,2). Out of 66 population pairs 52 were found to be genetically different significantly. This level of significant differentiation has not been reported yet in any other study conducted on European and African honeybee populations. High allelic ranges, and high divergence indicate that Anatolia is a genetic centre for C lineage honeybees. We suggest that certain precautions should be taken to limit or forbid introduction and trade of Italian and Carniolan honeybees to T&uuml / rkiye and Cyprus in order to preserve genetic resources formed in these territories in thousands of years. Effectivity at previously isolated regions in Artvin, Ardahan and Kirklareli was confirmed by the high genetic differentiation in honeybees of these regions. Genetically differentiated Karaburun and Cyprus honeybees v and geographical positions of the regions make these zones first candidates as new isolation areas.
169

Regional and Local-Scale Population Genetic Structure of a Primitive Teleost, the African Bonytongue (Heterotis niloticus), in Rivers of West Africa

Carrera, Elizabeth 2012 August 1900 (has links)
The African bonytongue (Heterotis niloticus), one of two living species of the primitive teleost family Arapaimidae, constitutes an important artisanal and commercial fishery in West Africa. This species has also been proposed for wide aquaculture use in Africa. Despite its importance, information on the levels of genetic differentiation for this fish in Benin is lacking, which can contribute to its conservation and management. In this study, regional and local scale genetic differentiation of the African bonytongue in Benin, West Africa, was examined using six microsatellite markers. In total, 221 H. niloticus individuals were sampled from 12 localities in Benin that include three river basins: Oueme-So (ten localities sampled); Mono (one locality); and Niger (one locality). The results showed a high degree of genetic differentiation between African bonytongue samples from the three river basins, which was expected given the barriers for dispersal for aquatic organisms. For the Oueme-So floodplain, they indicate high and homogeneous gene flow, suggesting that seasonal flooding facilitates gene flow across this region. The information obtained from this study will be useful for defining management units for H. niloticus in Benin, and caution against the translocation of individuals from different basins.
170

Population genetic structure of North American broad whitefish, Coregonus nasus (Pallas), with emphasis on the Mackenzie River system

Harris, Les N. 11 1900 (has links)
Broad whitefish, Coregonus nasus, is an important subsistence fish species in Arctic North America, yet virtually nothing is known regarding the genetic population structure of Nearctic populations of this species. In this thesis, microsatellite DNA variation was assayed among 1213 broad whitefish from 47 localities throughout North America, with emphasis on the Mackenzie River system, Northwest Territories. Specifically, I examined geographic variation in allele frequencies to assess how historical factors (Pleistocene glaciations) have shaped the current structuring of genetic variability and population differentiation. Microsatellite data was also used to resolve the relative contributions of broad whitefish populations to subsistence fisheries in the Mackenzie River system. Overall, broad whitefish exhibit relatively high intrapopulation microsatellite variation (average 12.29 alleles/locus, average HE = 0.58) and there were declines in these measures of genetic diversity with distance from putative refugia suggesting historical factors, namely post-glacial dispersal, have influenced current microsatellite variation. Interpopulation divergence was low (overall FST = 0.07), but the main regions assayed in this study (Russia, Alaska, Mackenzie River and Travaillant Lake systems) are genetically differentiated. Strong isolation-by-distance among samples was resolved when including only those populations occupying former Beringia, but not when assaying those at the periphery of the range in the Mackenzie River system, suggesting that broad whitefish in the Mackenzie system have not occupied the region long enough since their invasion post-glacially to have approached equilibrium between gene flow and drift. Mixture analysis indicated that most fish from the lower Mackenzie River subsistence fishery originated from the Peel River, highlighting the importance of this tributary. Additionally the mixture analysis provides evidence for a putative riverine life history form in the Mackenzie River. My results indicate that glaciation and post-glacial colonization have been important in shaping the current genetic population structure of North American broad whitefish. They also illustrate the utility of microsatellite DNA to delineate population structure and patterns of genetic diversity in recently founded populations in addition to resolving contributions to fisheries. My data also support the hypothesis that there are several designatable units of conservation among broad whitefish populations and that management strategies should be implemented accordingly.

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