Dissertations / Theses on the topic 'Population structure'
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Håkansson, Nina. "Population growth : analysis of an age structure population model." Thesis, Linköping University, Department of Mathematics, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-4392.
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This report presents an analysis of a partial differential equation, resulting from population model with age structure. The existence and uniqueness of a solution to the equation are proved. We look at stability of the solution. The asymptotic behaviour of the solution is treated. The report also contains a section about the connection between the solution to the age structure population model and a simple model without age structure.
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Cole-Showers, Curtis Lanre. "Population structure and demographics in Nigerian populations utilizing Y-chromosome markers." University of the Western Cape, 2014. http://hdl.handle.net/11394/5326.
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Philosophiae Doctor - PhDNigeria is peopled by ethnically and linguistically diverse populations of which little were known until the last few millennial. The absence of major natural geographical barrier increases the possibility of the populations being affected by the same demographic events. The aim of this thesis was to ascertain the genetic variations and demographics in five major Nigerian populations using Y-markers. This was done by determining the genetic structures of the Afro-asiatic speaking Hausa (n=78) of Northern Nigeria and the Niger Congo speaking populations of Igbo (n=119), Yoruba (n=238), Bini (n=13) and Ijaw (n=15) of Southern Nigeria all spread over 22 geographical origins and four (North, South east, south west and South south) geographical regions. They were compared with more than 2000 individuals from 46 populations of 20 other African and Middle Eastern countries, in published literature. The Scientific Working Group on DNA Analysis Methods (SWGDAM) recommended Y-Short Tandem Repeats (STRs) and nine Y-Single Nucleotide Polymorphisms (SNPs) haplogroups were typed with multiplex Polymerase Chain Reaction (PCR), Restriction Fragment Length Polymorphisms (RFLP) and High Resolution Melting (HRM). Summary statistics and measures of diversity were determined. Population structure was assessed with Population Pairwise Differences, hierarchical Analysis of Molecular Variance, Multidimensional scaling and correspondence analysis plots. Mantel’s test was used to assess the correlation of genetic distances with geographic distances. Demographic inferences were assessed with lineage based Network reconstruction, Spatial autocorrelation plots, effective migrants per population and both Inter and Intra-lineages Times to the Most Recent Common Ancestor (TMRCA). The patterns of diversity of the Y-markers showed a North-South gradient and a notable sub-structure among the Hausa populations. The Niger-Congo speakers displayed rare presence of haplogroups R and E1b1b but a preponderance of E1b1a7. Overall, the Y markers showed high diversities and significant genetic sub-structure within the Hausa populations of Nigeria with stronger linguistic than geographical bias. The demographic evaluations gave credence for genetic validation of both historical records and archeological findings among these Nigerian populations. These populations showed stronger affiliations with other sub-Saharan African populations rather than with North African or Middle Eastern populations, lacking evidence for the Middle Eastern origins of the male founders of these populations. Finally, the contribution of these Nigerian dataset would greatly enhance the Africa meta-population on the YHRD with more than 274 new haplotypes of forensic estimation significance.
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Sester-Huss, Elisabeth Mariko [Verfasser], and Peter [Akademischer Betreuer] Pfaffelhuber. "Population genetic models with selection, fluctuating environments and population structure." Freiburg : Universität, 2020. http://d-nb.info/1206095830/34.
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Piskol, Robert. "Structural and population genetic determinants of RNA secondary structure evolution." Diss., lmu, 2011. http://nbn-resolving.de/urn:nbn:de:bvb:19-130532.
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McVeigh, Helen Patricia. "Mitochondrial DNA and salmonid population structure." Thesis, Queen's University Belfast, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.352951.
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Watkins, Eleanor Rose. "The population structure of bacterial pathogens." Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:8ab53aa1-c55f-40bc-ab4f-ec2766b37252.
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Populations of many bacterial pathogens are structured into discrete strains despite frequent genetic exchange. Although insights from several studies suggest that different selection pressures operate in different areas of the genome, few theoretical and conceptual frameworks of bacterial population structure examine the effects of distinct competitive processes acting on different loci in the genome, and fewer still have considered the metabolic genes despite their increasingly-recognised importance in virulence. Buckee et al. (2008) investigated the combined effects of ecological competition operating at metabolic genes and immunological competition at antigenic genes on strain diversity using a stochastic model. A key prediction was that prevalent strains should show stable, non-overlapping associations between alleles of antigenic and metabolic genes. In this work, the roles of ecological and immunological competition in structuring bacterial pathogen populations is explored further using a multidisciplinary approach of mathematical modelling and whole genome analysis, focusing in particular on the well-characterised pathogens Neisseria meningitidis and Streptococcus pneumoniae as detailed case studies. We find support for the hypothesis that ecological and immunological competition play roles in structuring pathogen populations - even if present at relatively low levels - including support at the whole genome level. After extending the mathematical framework to encompass virulence-associated genes, we explore the effects of strain-targeted vaccination. We find that metabolic and virulence-associated genes from vaccine-strains are observed following vaccination in association with non-vaccine strains. The final chapter demonstrates how multilocus mathematical models coupled with whole genome analysis can be used together to gain additional insight into the evolution and population structure of bacterial pathogens.
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Baric, Michelle B. "Population Structure in the Cincinnati area." University of Cincinnati / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1367945142.
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Morgan, Lee W. "Allozyme Analysis of Billfish Population Structure." W&M ScholarWorks, 1992. https://scholarworks.wm.edu/etd/1539617645.
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Nussey, Daniel H. "Phenotypic plasticity and population genetic structure in a wild vertebrate population." Thesis, University of Edinburgh, 2005. http://hdl.handle.net/1842/15544.
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My thesis focuses on maternal phenotypic plasticity in two neonatal traits and population genetic structure at different spatial scales in a wild red deer (Cervus elaphus) population on the Isle of Rum, Scotland. Specifically, I present: • An analysis of offspring birth weight-spring temperature plasticity in female red deer using linear regression to measure individual reaction norms. I found evidence of variation in plasticity between females and show that early experiences of high population density reduce female plasticity. • The description of a mixed-effects linear model approach to analysing phenotypic plasticity from a reaction norm perspective, and application of this model to birth date in the Rum deer population. I use the model to examine variation in phenotypic plasticity between females and selection on plasticity at different population density levels. • An examination of population history and structure in red deer from across the Isle of Rum using mitochondria) DNA and microsatellite markers. Analysis revealed that deer in this introduced population came from geographically isolated ancestral populations, and there was genetic evidence for strongly male-biased dispersal. Recent management practices on the island may have led to spatial variation in effective male dispersal on Rum. • A comparison of fine-scale spatial genetic structure between male and female deer in the North Block study area using microsatellite markers and census data. There was evidence of structure at extremely fine spatial scales amongst females but not males, and a decline in the structure amongst females over time. • An analysis of the spatial distribution of different mtDNA haplotypes in male and female red deer across the North Block. There was evidence for spatial structuring of haplotypes in both sexes.
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Beisswanger, Steffen. "Selection and population structure in Drosophila melanogaster." Diss., [S.l.] : [s.n.], 2006. http://edoc.ub.uni-muenchen.de/archive/00006131.
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Burnett, W. J. "Population structure and species delimitation of Zoanthidea." Thesis, Swansea University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.636184.
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Zoanthidea (Cnidaria, Anthozoa, Hexacorallia) are common on tropical rocky shores and coral reefs. Large numbers of nominate species exist and many are difficult to identify. I used a genetic approach to examine population structure and taxonomy of zoanthids from the Great Barrier Reef and Torres Strait regions of Australia. Genetic population structure was investigated over two different spatial scales, using allozyme electrophoresis at seven polymorphic loci. I collected Palythoa caesia samples from 20 reefs spread over 1800 km. Results show that genetic differentiation among reefs is low but statistically significant, primarily due to variation in two populations. Population structure is characterised by genetic patchiness against a background of high gene flow. In a second study I collected Zoanthus coppingeri samples from three localities. Populations show evidence of asexual reproduction but are not dominated by successful clones. Sites separated by 50 m are genetically differentiated. Gene flow prevents fixed gene differences arising among populations of both these species. Fixed differences in taxonomic surveys (below) are therefore strong indicators of species boundaries. Eight species, from 19 localities throughout the Great Barrier Reef and Torres Strait, were genetically delimited using allozyme analysis of 14 loci. These species are separated by fixed gene differences. Genotype frequencies within species conform to Hardy-Weinberg predicted ratios. There is considerable morphological variation within species. Five species are identified in the family Zoanthidae: Palythoa caesia, Protopalythoa mutuki, Sphenopus marsupialis, Zoanthus coppingeri and Z. vietnamensis. These are probable senior synonyms of eighteen nominate species. Two Protopalythoa species remain unidentified. The eighth species, Parazoanthus dichroicus, is in the Parazoanthidae. A key to species is given. Phylogenetic analysis of zoanthid species used allozyme data and sequence data from 28S rDNA. I discuss results in the light of previous views of zoanthid systematics.
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Hughes, Mark. "Population structure and speciation in Begonia L." Thesis, University of Glasgow, 2002. http://theses.gla.ac.uk/6194/.
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In order to examine population structure (micro-evolution) in Begonia and its congruence to higher patterns of diversity (macro-evolution), nuclear microsatellite markers have been isolated and applied to two Begonia species, B. socotrana and B. sutherlandii. Begonia socotrana is endemic to the Haggeher Mountains of the island of Socotra in the Indian Ocean, where it has a total range of less than 10 x 15 km. Population surveys have highlighted the need for its conservation status to be reassessed, and it is proposed to reduce its status from 'endangered' to 'least concern'. Population genetic analyses using microsatellite data show a significant degree of population structure (RST= 0.081, P<0.01; q=0.096, P<0.01) and significant isolation by distance, even over small spatial scales. The pattern of isolation by distance could be due to restricted gene flow, or the result of small scale vicariance events in the fragmented peaks of the Haggeher Mountains during climate change and resulting altitudinal migration. Begonia sutherlandii is native to eastern and southern Africa, where it is restricted to shaded, moist banks in indigenous forest. A high degree of population structure was found (q=0.482, P<0.001; RST=0.634, P<0.001), which along with a high number of private alleles reflects the severe isolation of populations in a patchily distributed forest habitat. Population relationships appear to be strongly governed by the history and continuity of forest cover in the region. The population genetic studies of B. socotrana and B. sutherlandii show a strong correlation of genetic variation with geography which reflect patterns seen at larger scales. The correlation of micro and macro evolutionary patterns is congruent with a hypothesis of restricted gene flow promoting speciation in Begonia.
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Purves, Drew William. "Local spatial structure and plant population dynamics." Thesis, University of York, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251813.
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Barker, Margaret. "Population structure of the Bacillus cereus group." Thesis, Heriot-Watt University, 2006. http://hdl.handle.net/10399/2145.
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The Bacillus cereus group of bacteria comprises B. anthracis, B. cereus, B. mycoides, B. pseudomycoides, B. thuringiensis and B. weihenstephanensis. Species status has been allocated to these taxa largely according to pathogenic properties. B. anthracis is the causative agent of anthrax in ungulates and humans. B. thuringiensis is primarily an insect pathogen and B. cereus is associated with food poisoning and occasionally soft tissue infections in humans. One hundred and forty-six strains of the B. cereus group were examined by multilocus sequence typing (MLST) in which partial sequences for seven housekeeping genes (glpF, gmk, ilvD, pta, pur, pycA and tpi) were generated to provide a definitive sequence type (ST) for each strain. Statistical analyses of the data using pairwise comparisons between groups for (i) Fst (gene flow), (ii) shared mutations and (iii) fixed differences confirmed that the present designation of separate species status for members of the B. cereus group was inappropriate. Comparison of neighbour joining (NJ) trees derived from the concatenated sequence data with trees constructed for each allele individually indicated limited recombination between strains and a largely clonal structure to the group. Three major clades were recovered: clade 1 was made up of B. anthracis, B. cereus and rare B. ringiensis strains; clade 2 comprised a heterogeneous mixture of B. thuringiensis and B. cereus strains while clade 3 was composed of strains of B. cereus, B. mycoides and B. weihenstephanensis. Two B. pseudomycoides strains were distant outliers from the main tree. Four lineages were recognised in both clades 1 and 2 based on shared mutations within the lineages and fixed differences between them. B. anthracis strains and the emetic toxin-producing strains of B. cereus formed two clones within clade 1. A clonal group of entomopathogenic B. thuringiensis strains was identified in clade 2 and named the ‘Sotto’ lineage (after the predicted founder group). Strains of B. cereus that had been isolated from human wound infections and septicaemia, on the other hand, were distributed over clades 1 and 2, and were not restricted to a particular clonal group. Similarly, some serotypes of B. thuringiensis were found to have a clonal structure while others were heterogeneous. Representative strains from several serotypes of B. thuringiensis were examined by the RAPD (random amplified polymorphic DNA) method. Serovars israelensis and thuringiensis were strongly clonal, morrisoni and tolworthi were partially clonal while darmstadiensis and canadensis were heterogeneous. Serotype, MLST profile and RAPD did not always correlate with delta-endotoxin cry gene content. This may be due to the cry genes being located on plasmids and subject to transfer between strains. MLST does not support the separate species status of B. anthracis, B. cereus, B. mycoides, B. pseudomycoides, B. thuringiensis and B. weihenstephanensis and an alternative classification based on DNA sequence data is proposed based on three main clades with nine distinct lineages. The proposed lineages were named to be consistent with current nomenclature, as far as possible.
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Olson, Ewan Sinclair. "On the population structure of Mycobacterium tuberculosis." Thesis, University of Glasgow, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265638.
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The thesis is based on the results of analysis of a collection of Scottish isolates by pulsed- field gel electrophoresis and also by IS6110 Southern blotting. It also contains a review of the literature on Mycobacterium tuberculosis complex with an emphasis on strain typing and of the literature on population structures of bacteria. Based on the results and the literature review the following conclusions are drawn: 1. The population structure of Scottish isolates of the species Mycobacterium tuberculosis is clonal. 2. The genetic diversity of the Scottish isolates is so limited that the population structure forms a single clone. 3. Evidence is presented that the clone is not confined to Scotland and that all members of the species may be part of a single clone. 4. The work presented supports the hypothesis that the species Mycobacterium bovis is not a distinct species but a biovar of Mycobacterium tuberculosis.
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Karlsson, Anton. "Population Models with Age and Space Structure." Thesis, Linköpings universitet, Matematik och tillämpad matematik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-134926.
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In this thesis, basic concepts of populational models are studied from a theoretical point of view, especially the long term behaviours. All models are at least time dependent with additional age structure, spatial structure. The last model which is an extension of the von Foerster equation, is dependent on all o f these structures and have a long-term solution for large values of time. Modeling population is a frequent subject in modern biology. It is hard to create a model that appears as realistic as possible. First one might consider that a population size is governed by the current size of the population, along with rates of how each individual contributes (give birth), so that the population increases. and how frequent an individual dies, causing the population to decrease in size. However these sort of models can only describe the size of population in a shorter span of time.
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Luna, Hernandez Angela. "Multivariate structure preserving estimation for population compositions." Thesis, University of Southampton, 2016. https://eprints.soton.ac.uk/404689/.
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This document introduces a new Structure Preserving Estimator for Small Area compositions, using data from a proxy and a sample compositions. The proposed estimator, the Multivariate Structure Preserving Estimator (MSPREE), extends the two main SPREE-type estimators: the SPREE and the GSPREE. The additional flexibility of the MSPREE may lead to estimates with less MSE than its predecessors. An extension of the MSPREE including cell specific random effects, the Mixed MSPREE (MMSPREE), is also presented, in an attempt to further reduce the size of the bias when the associated sample size allows for it. In order to estimate the variance components governing the variance structure of the random effects in the MMSPREE, an unbiased moment-type estimator is proposed. Furthermore, an estimator for the variance of the MSPREE, as well as methodologies to evaluate the unconditional and finite population MSE of both MSPREE and MMSPREE, are developed. The behaviour of the proposed estimators is illustrated in a controlled setting via a simulation exercise, and in a real data application.
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Giemza, Joanna. "Fine-scale genetic population structure in France." Thesis, Nantes, 2019. http://www.theses.fr/2019NANT1007/document.
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La structure génétique à fine échelle des populations humaines est intéressante pour deux raisons principales : 1) elle reflète des événements historiques et démographiques, 2) elle informe la recherche sur les études d’association de maladies. Cette thèse a pour objectif de procéder à une analyse approfondie de la structure génétique de la population de France métropolitaine dans un premier temps, en de façon plus détaillée de la population du nord-ouest de la France, et de mettre en lumière les événements historiques, démographiques et culturels qui l’ont façonnés, en tirant parti de trois jeux de données (SU.VI.MAX/3C et PREGO). Au niveau de la France, nous rapportons la corrélation entre les données génétiques et les lieux de naissance d’individus appartenant à deux cohortes françaises indépendantes (1 414 et 770 individus) et identifions six groupes, concordants entre les jeux de données. La deuxième étude tire parti de la cohorte PREGO, qui comprend 3 234 personnes ayant trois générations d’ascendance liée à des régions spécifiques du nord-ouest de la France. Je révèle une structure à fine échelle à un niveau sans précédent (154 sous-populations).historique de la France et des explications potentielles de la prévalence de différentes maladies dans cette région du nord-ouest. Dans l’ensemble, mes travaux de thèse indiquent des niveaux substantiels de stratification de la population dans une région géographiquement limitée, probablement en raison de différents antécédents démographiques dans la régionFine-scale genetic structure in human populations is interesting for two main reasons: 1), it reflects historical and demographic events, 2) it informs research on disease association studies. This thesis aims to perform a thorough analysis of the genetic structure of the population from continental France, in particular Northwestern France, and shed light on the historical, demographic and cultural events that have shaped it, by taking advantage of three genome-wide datasets (SU.VI.MAX/3C and PREGO) At the country level we report the correlation between genetic data and birthplaces of individuals in two independent French cohorts (1,414 and 770 individuals in SU.VI.MAX and 3C, respectively) and identify six clusters, concordant between datasets, and may correspond to ancient political, cultural and geographical borders. The second study takes advantage of the PREGO cohort including 3,234 individuals with three generations of ancestry linked to specific regions of Northwestern France and reveals fine-scale structure at an unprecedented level (154 subpopulations). The resulting genetic clusters and the characterisation of their effective population size and ancestry proportions compared to other European groups provide important and novel insights into the historical peopling of France and potential explanations for different disease prevalence within this northwestern region. Overall, my thesis work indicate substantial levels of population stratification within a geographically limited region likely caused by different demographic histories across the region
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Hobbs, Geoffrey I. "Population genetic structure of a recovering otter (Lutra lutra) population in the UK." Thesis, Cardiff University, 2010. http://orca.cf.ac.uk/54957/.
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The aim of this study was to identify the genetic structure of the expanding UK otter population. To do this I undertook detailed analysis of methodologies from the emerging field of landscape genetics. I compared the Bayesian Clustering methodologies, culminating in recommendations on how to interpret the results of the available software. Further to this I devised a novel progressive partitioning method, incorporating GIS (geographical information systems) to allow the clustering results of the different software packages to be compared and combined, producing a more robust interpretation of clustering results. The effect of landscape features on otter movement was explored using GIS by mapping individuals on cost grids of landscape features and identifying the degree to which dispersal is influenced by the landscape, by correlating effective distance with genetic distance. Inspiration was taken from recent advances in landscape genetics and required the development of these techniques to achieve the aims of the project as a result this thesis also contributes to the advancement of this field of research. This study identified that there are four regional otter populations in the UK with little or no gene flow between them. The recovering otter populations in the strongholds of North England, Wales and Borders and Southwest England appear not to be contributing to expansion of the once fragmented, unviable population in Central England. This population has been subject to captive bred re-introductions by the Otter Trust. Despite the apparent success of the reintroductions, questions have arisen about the origin of the released individuals and their conservation implications. Further sub-structuring was identified in all of the regional populations and potential reasons explored. The Wales and Borders region was singled out for further analysis, to identify the influence of landscape features on the genetic structure. The highly urban areas of southeast Wales appeared to be acting as a barrier to dispersal between sub-regions. Correlations between genetic and effective distances (created from resistance-to-movement surfaces) suggest that upland habitat and slope contribute to the genetic sub-structuring the Cambrian and Brecon Beacon mountain ranges act as permeable barriers, restricting the amount of gene flow and help to create the identified sub-regions.
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Nava, Imelda L. "Porichthys notatus bioluminescence capability, population structure, and systematics /." Diss., Restricted to subscribing institutions, 2009. http://proquest.umi.com/pqdweb?did=1997749611&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
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Chen, Hong. "Population structure and species description of aquatic Sphingomonadaceae." Diss., lmu, 2012. http://nbn-resolving.de/urn:nbn:de:bvb:19-139494.
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Johnson, Mollie. "Population Structure of Limenitis Butterflies in Hickman, Kentucky." TopSCHOLAR®, 2008. http://digitalcommons.wku.edu/theses/368.
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Two species of Limenitis butterflies occur along the Mississippi River at Hickman, Kentucky: the viceroy, L. archippus, and the red-spotted purple, L. arthemis astyanax. Limenitis archippus occurs at a frequency that is 10-30 times more abundant than its congener, L. arthemis astyanax. Interspecific matings between L. archippus and L. arthemis astyanax are very rare in the wild and give rise to a hybrid form Limenitis archippus X L. arthemis astyanax form rubidus. Only 7 heterospecific pairings between the parental species and 72 "rubidus" individuals have been documented in the wild in all of North America. Of these documented cases, 2 heterospecific mating pairs and 2 rubidus individuals have been collected along a single 100 meter stretch of the Mississippi River at Hickman over the last several years, suggesting that this may be a "hybridization hotspot". Molecular analysis of mitochondrial DNA haplotype, nuclear SNPs and nuclear Randomly Amplified DNA Fingerprints (RAF) from the 2 Hickman rubidus butterflies confirms that they are both Fi hybrids and that L. archippus was the maternal parent for each specimen. I am interested in discovering the extent to which hybridization has allowed gene flow between L. archippus and L. arthemis astyanax at this location. Ten individuals of each species were collected at Hickman and analyzed for both mitochondrial DNA haplotype and nuclear Randomly Amplified DNA Fingerprint (RAF) markers. The results of my analyses suggest that there may be some ongoing gene flow between these two species of Limenitis at this site.
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Kyle, Christopher J. "Molecular population genetic structure of northeastern Pacific Littorina." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ27518.pdf.
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Idid, Mohammed Rizman. "Phylogenetics and population structure of Lake Malawi cichlids." Thesis, University of Hull, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.418795.
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Bolt, Frances. "The population structure of the Corynebacterium diphtheriae group." Thesis, University of Warwick, 2009. http://wrap.warwick.ac.uk/1759/.
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A multi-locus sequence typing scheme was designed for the Corynebacterium diphtheriae group comprising C. diphtheriae, C. ulcerans and C. pseudotuberculosis. Five MLST genes (atpA, dnaE, fusA, odhA and rpoB) were analysed to resolve the inter-species relationships of the three organisms. No alleles were shared between the species and MLSA analysis indicated that they represent distinct populations with no evidence of recombination between the organisms. One hundred and fifty four C. diphtheriae isolates were analysed by MLST using the same five loci and two additional genes (dnaK and leuA). The data derived was in concordance with previous ribotyping studies and identified two clonal complexes associated with diphtheria outbreaks. No correlation between ST and toxin production or clinical presentation was observed. In contrast to the biovars gravis, mitis and intermedius the atypical belfanti strains were distinct by phylogenetic analysis. Although two C. diphtheriae cultures isolated from a horse clustered with the human strains four isolates obtained from two cats shared no alleles with the other isolates examined. MLST analysis of 69 C. ulcerans isolates using the five MLST genes and the virulence determinant phospholipase D (PLD) revealed that veterinary and human isolates were not genetically distinct. As with the C. diphtheriae population recombination was shown to play an important role in the evolution of the organism. The 73 C. pseudotuberculosis isolates were examined with the five MLST loci, pld and two genes within the Fe acquisition operon; fagCand fagD. The nitrate negative and positive strains were distinguished by MLST but shared ancestry was apparent as the same alleles were identified in two to three of the genes. MLST supported previous studies which indicate that C. pseudotuberculosis biovar ovis is a genetically homogenous species. This is the first MLST scheme designed for the C. diphtheriae group and the first to encompass multiple species within the Corynebacterium genus. MLST provides a useful tool for the discrimination of the three species and will enable the detection of genetic exchange events between and within the organisms.
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Cheshire, J. A. "Population structure and the spatial analysis of surnames." Thesis, University College London (University of London), 2011. http://discovery.ucl.ac.uk/1324522/.
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Geographers have largely overlooked surnames (family names), and their geographic concentrations, as a valuable source of data to indicate the spatial structure of populations. This thesis seeks to provide a substantive contribution to the geographical literature by demonstrating how quantitative spatial analysis of surname data can be used as an aid to understanding population structure at a range of scales from the regional to the continental. The primary purpose of this research is not to develop detailed case studies or to investigate specific examples of population characteristics considered interesting for their novelty: rather, the core concern is to focus on the identification or confirmation of generalised trends. Much of the current research that uses surnames (for example in population genetics) contains a geographical element, yet stops short of exploiting and accommodating the effect of scale, shape and size of spatial units. The application of computationally intensive spatial analysis techniques to a comprehensive and innovative dataset (see worldnames.publicprofiler.org) makes it possible to address these issues for the first time. The thesis develops and applies a robust analytical and methodological framework for the analysis of surnames as a primary data source. Applications of the research are used to demonstrate the utility of surnames in studies of population genetics, in migration research, as well as in the spatial analysis of large datasets more generally.
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Smith, Olutolani. "Population genetics and structure of the Sumatran tiger." Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/11756.
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The two key determinants of population persistence in fragmented landscapes are population size and connectivity. Populations with high levels of genetic variation and large population size are expected to have a lower risk of extinction. Similarly, populations with high rates of connectivity are expected to persist long-term. For many elusive landscape species it is difficult to obtain direct estimates of these parameters, but genetic sampling can offer powerful indirect assessments. Whilst these techniques have been applied to the study of many wide-ranging carnivores, this study represents the first example in the Sumatran tiger (Panthera tigris sumatrae). Extensive field surveys were conducted to collect faecal samples from several Tiger Conservation Landscapes and protected areas on Sumatra. Samples were then processed according to optimised protocols to obtain reliable results. In order to quantify extinction risk I first estimated genetic variation and effective population size using microsatellite loci. I also determined relative levels of connectivity using estimates of differentiation (FST), gene flow and genetic clustering. Results indicate that Sumatran tigers have high levels of genetic variation and that their effective population size is within the expected range. There is very little population structure and there is no obvious evidence for barriers to dispersal. The Batang Hari/Kerinci Seblat ecosystem emerged as a potential source population and in contrast there was some evidence of isolation affecting the population of Way Kambas NP in the extreme south of the island. Overall, despite high levels of human land cover conversion over the past 20-30 years, few genetic changes have been expressed in the Sumatran tiger. The immediate threat to tigers is not the loss of genetic diversity, but the rapidly declining area of suitable habitat in which they can survive.
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Rimal, Suraj. "POPULATION STRUCTURE INFERENCE USING PCA AND CLUSTERING ALGORITHMS." OpenSIUC, 2021. https://opensiuc.lib.siu.edu/theses/2860.
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Genotype data, consisting large numbers of markers, is used as demographic and association studies to determine genes related to specific traits or diseases. Handling of these datasets usually takes a significant amount of time in its application of population structure inference. Therefore, we suggested applying PCA on genotyped data and then clustering algorithms to specify the individuals to their particular subpopulations. We collected both real and simulated datasets in this study. We studied PCA and selected significant features, then applied five different clustering techniques to obtain better results. Furthermore, we studied three different methods for predicting the optimal number of subpopulations in a collected dataset. The results of four different simulated datasets and two real human genotype datasets show that our approach performs well in the inference of population structure. NbClust is more effective to infer subpopulations in the population. In this study, we showed that centroid-based clustering: such as k-means and PAM, performs better than model-based, spectral, and hierarchical clustering algorithms. This approach also has the benefit of being fast and flexible in the inference of population structure.
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Penington, Sarah. "Branching processes with spatial structure in population models." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:361e5c58-e6dd-47a0-9a52-303e897547e8.
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We consider three different settings for branching processes with spatial structure which appear in population models. Firstly, we consider the effect of adding a competitive interaction between nearby individuals in a branching Brownian motion. Each individual has a mass which decays when other individuals are nearby. We study the front location: the location at which the local mass density drops to o(1). We show that there are arbitrarily large times t at which the front location is order of t^(1/3) behind the maximum displacement of a particle from the origin. Secondly, we study the strength of selection in favour of a particular allele in a spatially structured population required to cause a detectable trace in the patterns of genetic variation observed in the contemporary population. We suppose that the effective local population density is small. We show that whereas in dimensions at least three, selection is barely impeded by the spatial structure, in the most relevant dimension, d=2, selection must be stronger (by a factor of log(1/m) where m is the neutral mutation rate) if we are to have a chance of detecting it. Finally, we model the behaviour of what are known in population genetics as hybrid zones. These occur when two genetically distinct groups are able to reproduce, but the hybrid offspring have a lower fitness. We prove that on an appropriate time and space scale, the hybrid zone in our model evolves approximately according to mean curvature flow. We also give a probabilistic proof of a (well-known) analogous result for a special case of the Allen-Cahn equation. In the last two cases, we use the spatial Lambda-Fleming-Viot process to model the population (with different selection mechanisms), and our proofs rely on a duality with a system of branching and coalescing particles.
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Monclova-Santana, Cecilia. "Population Structure of Uromyces appendiculatus in North Dakota." Diss., North Dakota State University, 2019. https://hdl.handle.net/10365/29519.
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North Dakota is the lead producing state of common bean in the USA, accounting for 43% of national production. Bean rust is caused by the autoecious, macrocyclic fungus Uromyces appendiculatus (Pers.:Pers.). All pathogen spores stages have been observed in North Dakota, but it is unclear how frequently sexual reproduction occurs. Traditionally, genetic resistance is the preferred management method. Sixty-seven percent of the 119 U. appendiculatus single pustule isolates collected in 2015 and 2016 were classified phenotypically as race 20-3. Virulence phenotypes of race 20-3 isolates ranged from hypersensitive to small pustules (0.2-0.3mm) on Early Gallatin, PC-50, Mexico 235, and Mexico 325 rust differential lines. This variation suggests more pathogen diversity is present than is discernable via traditional race classifications. The remaining 33% of U. appendiculatus isolates belonged to 18 additional races. Genome Wide Association Studies were conducted with the advanced breeding lines from the NDSU bean breeding program, the Middle American diversity panel, and a subset of Andean diversity panel reaction to races 20-3, 29-3 and 27-7. Significant SNP markers on chromosomes Pv01, Pv04, Pv06, Pv08, Pv10, and Pv11 were identified using genome wide association mapping. RAD-GBS was performed on 84 single pustule U. appendiculatus isolates using the Ion-Torrent S5 sequencing platform. A de novo assembly was performed on a single isolate of race 20-3 to generate reference sequence tags for variant calling. The relatedness measure using an identity by state (IBS) matrix suggested the presence of diversity within and among the isolates belonging to the same race, providing further evidence that the U. appendiculatus population in North Dakota is undergoing sexual reproduction and is more diverse than virulence phenotypes suggest. Results from this research increase our understanding of population dynamics and diversity in phenotype and genotype of U. appendiculatus and will assist common bean breeding for rust resistance.North Dakota. Department of Agriculture
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Hammen, Jeremy J. L. "Genetic structure of Wisconsin's naturally recruiting walleye population /." Link to full-text, 2009. http://epapers.uwsp.edu/thesis/2009/Hammen.pdf.
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Thesis (M.S.)--University of Wisconsin--Stevens Point, 2009.Submitted in partial fulfillment of the requirements of the degree Master of Science in Natural Resources (Fisheries), College of Natural Resources.) Includes bibliographical references (leaves 52-63).
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Hubbard, Amelia R. "AN EXAMINATION OF POPULATION HISTORY, POPULATION STRUCTURE, AND BIOLOGICAL DISTANCE AMONG REGIONAL POPULATIONS OF THE KENYAN COAST USING GENETIC AND DENTAL DATA." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1337195794.
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Robinson, Emma Claire. "Characterising population variability in brain structure through models of whole-brain structural connectivity." Thesis, Imperial College London, 2010. http://hdl.handle.net/10044/1/5875.
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Models of whole-brain connectivity are valuable for understanding neurological function. This thesis seeks to develop an optimal framework for extracting models of whole-brain connectivity from clinically acquired diffusion data. We propose new approaches for studying these models. The aim is to develop techniques which can take models of brain connectivity and use them to identify biomarkers or phenotypes of disease. The models of connectivity are extracted using a standard probabilistic tractography algorithm, modified to assess the structural integrity of tracts, through estimates of white matter anisotropy. Connections are traced between 77 regions of interest, automatically extracted by label propagation from multiple brain atlases followed by classifier fusion. The estimates of tissue integrity for each tract are input as indices in 77x77 ”connectivity” matrices, extracted for large populations of clinical data. These are compared in subsequent studies. To date, most whole-brain connectivity studies have characterised population differences using graph theory techniques. However these can be limited in their ability to pinpoint the locations of differences in the underlying neural anatomy. Therefore, this thesis proposes new techniques. These include a spectral clustering approach for comparing population differences in the clustering properties of weighted brain networks. In addition, machine learning approaches are suggested for the first time. These are particularly advantageous as they allow classification of subjects and extraction of features which best represent the differences between groups. One limitation of the proposed approach is that errors propagate from segmentation and registration steps prior to tractography. This can cumulate in the assignment of false positive connections, where the contribution of these factors may vary across populations, causing the appearance of population differences where there are none. The final contribution of this thesis is therefore to develop a common co-ordinate space approach. This combines probabilistic models of voxel-wise diffusion for each subject into a single probabilistic model of diffusion for the population. This allows tractography to be performed only once, ensuring that there is one model of connectivity. Cross-subject differences can then be identified by mapping individual subjects’ anisotropy data to this model. The approach is used to compare populations separated by age and gender.
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Melling, T. M. "The ecology and population structure of a butterfly cline." Thesis, University of Newcastle upon Tyne, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377453.
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Gosney, Louise Mary. "Phylogeography and population structure of carabid beetle Pterostichus melanarius." Thesis, University of East Anglia, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.247110.
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Thomas, Scott. "Genetic Structure Due to Variation in Breeding Time in a Salamander Population." University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1386767741.
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Weir, D. A. "The population ecology and clonal structure of two grasses." Thesis, University of Liverpool, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.353346.
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Renwick, Juanita. "Population structure and genetic diversity of Southeast Queensland populations of the Wallum Froglet, Crinia Tinnula (Tschudi)." Thesis, Queensland University of Technology, 2006. https://eprints.qut.edu.au/16181/1/Juanita_Renwick_Thesis.pdf.
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Genetic diversity is a fundamental attribute that contributes to a species evolutionary survival. In recent times, conservation managers have recognized the need to preserve genetic diversity of declining species, and have also acknowledged the utility of genetic markers for describing genetic and ecological relationships within and among populations. Information obtained from genetic studies can be used in conjunction with information on population demography, land use patterns and habitat distribution to develop effective management strategies for the conservation of species in decline.
The wallum froglet, Crinia tinnula, is one of Australia's smallest habitat specialist anurans. In recent years there has been a dramatic decrease in population numbers of this species. The habitat to which C.tinnula is endemic ('wallum' habitat) is restricted to low coastal plains along the southeast Queensland and northern New South Wales coastline. As human populations in this region expanded, the coastal areas have undergone significant development and large areas of wallum habitat have been cleared. The effect has been to convert once largely continuous patches of coastal heathland in to a matrix of small habitat patches within an area undergoing rapid urban expansion.
This study aimed to document levels and patterns of genetic diversity and to define the population structure of C.tinnula populations within southeast Queensland, with the objective of defining possible conservation management units for this species. Results from 12S and COI mitochondrial markers clearly showed that two distinct evolutionary lineages of C.tinnula are present within southeast Queensland. The high level of divergence between lineages and strict geographic partitioning suggests long term isolation of C.tinnula populations. It is hypothesized that ancestral C.tinnula populations were once confined to wallum habitat refugia during the Pliocene resulting in phylogeographic delineation of 'northern' and 'southern' C.tinnula clades.
Populations within each geographic region show evidence of range contraction and expansion, with subsequent restricted gene flow. Levels of genetic diversity appear, largely, to be the product of historical associations rather than contemporary gene flow. A revision of the current systematics of C.tinnula is required to ensure that discrete population groups are recognized as distinct evolutionary lineages and will therefore be protected accordingly.
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Renwick, Juanita. "Population structure and genetic diversity of Southeast Queensland populations of the Wallum Froglet, Crinia Tinnula (Tschudi)." Queensland University of Technology, 2006. http://eprints.qut.edu.au/16181/.
Full textAbstract:
Genetic diversity is a fundamental attribute that contributes to a species evolutionary survival. In recent times, conservation managers have recognized the need to preserve genetic diversity of declining species, and have also acknowledged the utility of genetic markers for describing genetic and ecological relationships within and among populations. Information obtained from genetic studies can be used in conjunction with information on population demography, land use patterns and habitat distribution to develop effective management strategies for the conservation of species in decline. The wallum froglet, Crinia tinnula, is one of Australia's smallest habitat specialist anurans. In recent years there has been a dramatic decrease in population numbers of this species. The habitat to which C.tinnula is endemic ('wallum' habitat) is restricted to low coastal plains along the southeast Queensland and northern New South Wales coastline. As human populations in this region expanded, the coastal areas have undergone significant development and large areas of wallum habitat have been cleared. The effect has been to convert once largely continuous patches of coastal heathland in to a matrix of small habitat patches within an area undergoing rapid urban expansion. This study aimed to document levels and patterns of genetic diversity and to define the population structure of C.tinnula populations within southeast Queensland, with the objective of defining possible conservation management units for this species. Results from 12S and COI mitochondrial markers clearly showed that two distinct evolutionary lineages of C.tinnula are present within southeast Queensland. The high level of divergence between lineages and strict geographic partitioning suggests long term isolation of C.tinnula populations. It is hypothesized that ancestral C.tinnula populations were once confined to wallum habitat refugia during the Pliocene resulting in phylogeographic delineation of 'northern' and 'southern' C.tinnula clades. Populations within each geographic region show evidence of range contraction and expansion, with subsequent restricted gene flow. Levels of genetic diversity appear, largely, to be the product of historical associations rather than contemporary gene flow. A revision of the current systematics of C.tinnula is required to ensure that discrete population groups are recognized as distinct evolutionary lineages and will therefore be protected accordingly.
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Aldrich, Benjamin T. "Population genetics and colony structure of two Zootermopsis subspecies /." Search for this dissertation online, 2005. http://wwwlib.umi.com/cr/ksu/main.
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Choopun, Nipa. "The population structure of Vibrio cholerae in Chesapeake Bay." College Park, Md. : University of Maryland, 2004. http://hdl.handle.net/1903/1686.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2004.Thesis research directed by: Marine-Estuarine-Environmental Sciences. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Neuditschko, Markus. "A whole-genome population structure analysis within cattle breeds." Diss., lmu, 2011. http://nbn-resolving.de/urn:nbn:de:bvb:19-133991.
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Strand, Tanja. "European Black Grouse : MHC Genetic Diversity and Population Structure." Doctoral thesis, Uppsala universitet, Populationsbiologi och naturvårdsbiologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-160042.
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Black grouse Tetrao tetrix is a bird species composed of large, continuous as well as severely reduced and fragmented populations, making it an optimal species to investigate how genetic diversity is affected by habitat fragmentation. I have focused on genetic diversity in the Major Histocompatibility Complex (MHC) to measure the ability of the black grouse to respond to environmental changes. I partly characterized MHC class II in black grouse and found striking similarities with chicken MHC class II. I demonstrated that black grouse possess a similar compact MHC as chicken with few MHC class II B (BLB) and Y (YLB) loci. I did not find evidence of balancing selection in YLB so I concentrated further studies on BLB. I developed a PCR-based screening method for amplifying and separating expressed BLB alleles in European black grouse populations. Small fragmented populations had lost neutral genetic diversity (based on microsatellites and SNPs) compared to samples from the historical distribution and contemporary large populations. There was also a trend, albeit less pronounced, for reduced MHC diversity in these populations. Neutral markers in small isolated populations were affected by increased levels of genetic drift and were therefore genetically differentiated compared to other populations. MHC markers on the other hand, were not subjected to genetic drift to the same extent probably due a long historic process of balancing selection. Inferences of heterozygosity and evolutionary patterns as well as detailed correlations to reproductive success and diseases cannot be performed until MHC can be amplified in a locus-specific manner. Therefore, I developed a single locus sequence-based typing method for independently amplifying MHC class II B loci (BLB1 and BLB2). I found that BLB1 and BLB2 were duplicated in a common ancestor to chickens and black grouse and that these loci are subjected to homogenizing concerted evolution due to inter-genetic exchange between loci after species divergence. I could also verify that both BLB1 and BLB2 were transcribed in black grouse and under balancing selection. This collection of work has significance for future conservation of black grouse as well as research and management of zoonotic diseases.
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Searle, Laura. "Population structure and siderophore production in commensal Escherichia coli." Thesis, University of East Anglia, 2015. https://ueaeprints.uea.ac.uk/60797/.
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The factors involved in the diversity, transition and persistence of commensal Escherichia coli, both between and within hosts, are not fully understood. The aim of this project was to develop and use comparative approaches to investigate traits associated with colonisation of the gut by taking advantage of two collections of natural isolates of E. coli, the ECOR (host-associated) and GMB (plant-associated) collections. A new method for uniquely tagging and monitoring individual E. coli strains was developed to facilitate the assessment of large numbers of strains in complex environments, such as the gut. Competition studies between ‘barcoded’ strains show that this technique has a high sensitivity enabling the identification of E. coli present in the population at low levels, which may be undetected using currently available methods. Together with genome-wide association studies, barcoding is a powerful tool for identifying adaptive traits associated with the environment. One trait linked to E. coli gut colonisation is production of the siderophore enterobactin. Comparisons of siderophore production and the distribution of siderophore loci between the GMB and ECOR collections highlighted that faecal strains produce higher levels of siderophores and possess a larger number of siderophore systems at the population level. However, while our epidemiological data indicated a role for siderophore biosynthesis in the GI-tract, we did not observe significant differences in the competitiveness of siderophore biosynthesis mutants in a mouse model. Whether this is linked to the ability of mutants to cheat and use siderophores generated by the wild-type strain or to obtain iron through other ways remains to be determined. Overall, this study provides further details on the factors determining how the environment shapes the associated E. coli populations. This knowledge is essential to assess the relationship between the environment, the associated E. coli populations and the risk they represent to human health.
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Wang, Yean. "Molecular polymorphisms for phylogeny, pedigree and population structure studies." University of Sydney, 2007. http://hdl.handle.net/2123/1541.
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Doctor of PhilosophyA number of types of molecular polymorphisms can be used for studying genetic relationship and evolutionary history. Microsatellites are hypervariable and can be very useful tools to determine population structure, distinguish sibling species, as well as verifying parental relationships and pedigrees. However, while microsatellite polymorphisms are useful for solving relationships between populations within a species, relations among species or genera will probably be obscured due to a high degree of homoplasy —identity arising from evolutionary convergence not by descent. For long range evolutionary history, such as phylogeny from old world monkey to human, mtDNA markers may be better candidates. The aim of this thesis is to assess molecular polymorphisms of different types and their optimal use in different situations. Two widely separated taxa were used for testing –the green monkey Chlorocebus sabaeus, and the sibling dipteran flies Bactrocera tryoni and B. neohumeralis, known collectively as the Queensland fruit fly. In the present study a complete 16,550 bp mtDNA sequence of the green monkey Chlorocebus sabaeus is reported for the fist time and has been annotated (Chapter 2). Knowledge of the mtDNA genome contributes not only to identification of large scale single nucleotide polymorphisms (SNPs) (Chapter 4) or other mtDNA polymorphisms development, but also to primate phylogenetic and evolutionary study (Chapter 3). Microsatellites used for the green monkey paternity and pedigree studies were developed by cross-amplification using human primers (Chapter 5). For studies of population structure and species discrimination in Queensland fruit fly (Chapter 7), microsatellites were isolated from a genomic library of Bactrocera tryoni (Chapter 6) The total length of 16550 bp of complete mtDNA of the green monkey C. sabaeus, which has been sequenced and annotated here, adds a new node to the primate phylogenetic tree, and creates great opportunity for SNP marker development. The heteroplasmic region was cloned and five different sequences from a single individual were obtained; the implication of this are discussed. The phylogenetic tree reconstructed using the complete mtDNA sequence of C. sabaeus and other primates was used to solve controversial taxonomic status of C. sabaeus. Phylogenies of primate evolution using different genes from mtDNA are discussed. Primate evolutionary trees using different substitution types are compared and the phylogenetic trees constructed using transversions for the complete mtDNA were found close to preconceived expectations than those with transversions + transitions. The sequence of C. sabaeus 12SrRNA reported here agrees with the one published by ven der Kuyl et al. (1996), but additional SNPs were identified. SNPs for other regions of mtDNA were explored using dHPLC. Twenty two PCR segments for 96 individuals were tested by dHPLC. Fifty five SNPs were found and 10 haplogroups were established. Microsatellite markers were used to construct a genealogy for a colony of green monkeys (C. sabaeus) in the UCLA Vervet Monkey Research Colony. Sixteen microsatellites cross-amplified from human primers were used to conduct paternity analysis and pedigree construction. Seventy-eight out of 417 offspring were assigned paternity successfully. The low success rate is attributed to a certain proportion of mismatches between mothers and offspring; the fact that not all candidate fathers were sampled, the limitations of microsatellite polymorphisms; and weakness of the exclusion method for paternity assessment. Due to the low success rate, the pedigree is split into a few small ones. In a complicated pedigree composed of 75 animals and up to four generations with multiple links a power male mated with 8 females and contributed 10 offspring to the pedigree. Close inbreeding was avoided. Population structure within two species of Queensland fruit fly Bactrocera tryoni and Bactrocera neohumeralis (Tephritidae: Diptera) is examined using microsatellite polymorphisms. Queensland fruit flies B. tryoni and B. neohumeralis are sympatric sibling species that have similar morphological and ecological features. They even share polymorphism at the molecular level. Mating time difference is the main mechanism by which they maintain separate species. In the present study, 22 polymorphic and scorable microsatellites were isolated from B. tryoni and tested in the two species sampled from sympatric distribution areas. Pairwise genetic distance analysis showed explicit differentiation in allele frequencies between the two species, but very weak differences between conspecific populations. Gene flow is higher within B. tryoni than within B. neohumeralis, and gene exchange between the two species exists. An averaging linkage clustering tree constructed by UPGMA showed two major clusters distinguishing the two species, and it appears that population structure is highly correlated with geographic distance. The relationship between molecular markers, evolution, and selection are discussed using comparative studies within two large taxa: primate and insect. The degree of conservation and polymorphism in microsatellites varies between taxa, over evolutionary time.
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Parks, Wesley Ryan. "Structure of the Eastern U.S. Wheat Powdery Mildew Population." NCSU, 2008. http://www.lib.ncsu.edu/theses/available/etd-01032008-214715/.
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In the eastern U. S. and other wheat growing areas of the world, powdery mildew is a major constraint to the production of wheat. Currently, the most effective and economical means of control is to use resistant cultivars. Unfortunately, the diversity of the pathogen population enables the pathogen to overcome new resistance genes, often within several seasons of commercial deployment. Surveys to determine the virulence of the population to a set of resistance genes have been performed in many areas of the world. Often, differential frequencies of virulence at varying geographic areas are extended to infer a putative population structure. Due to selective pressure, virulence frequencies are poorly suited to high-resolution analysis of population structure and results may reflect regional cultivar choices and not underlying population phylogeny. A collection of 206 single-ascospore derived powdery mildew isoaltes were utilized to determine virulence frequencies at varying locations in the eastern U. S. Primers were developed to amplify coding sequences in order to assess single nucleotide polymorphisms within this population, which allowed allowed analyses of the distribution of presumably neutral genetic variation. Dendrograms based on Nei?s standard genetic distance (Gst) indicated clustering of virulence frequencies into northern and southern subpopulations, with North Carolina as the putative boundary between groups. DNA sequence based AMOVA analysis using groups derived from Hudson?s sequence based subdivision test (Snn) support this conclusion. Tests for population richness indicate greater haplotype diversity in Virginia and Delaware; a result with several possible explanations based on the known history of North American wheat cultivation.
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Carlsson, Jens. "Population genetic structure of brown trout in boreal ecosystems /." Umeå : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 2000. http://epsilon.slu.se/avh/2000/91-576-5884-6.pdf.
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Hume, Jennifer C. C. "Transmission studies and population structure in human malaria parasites." Thesis, University of Oxford, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.409801.
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Brierley, Andrew Stuart. "Aspects of genetic diversity and population structure of squid." Thesis, Bangor University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316589.
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Jan, Camille. "Population structure of swarming bats in relation to dispersal." Thesis, University of Leeds, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.540207.
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