Rozprawy doktorskie na temat „Genetic diversity”
Kliknij ten link, aby zobaczyć inne rodzaje publikacji na ten temat: Genetic diversity.
Utwórz poprawne odniesienie w stylach APA, MLA, Chicago, Harvard i wielu innych
Sprawdź 50 najlepszych rozpraw doktorskich naukowych na temat „Genetic diversity”.
Przycisk „Dodaj do bibliografii” jest dostępny obok każdej pracy w bibliografii. Użyj go – a my automatycznie utworzymy odniesienie bibliograficzne do wybranej pracy w stylu cytowania, którego potrzebujesz: APA, MLA, Harvard, Chicago, Vancouver itp.
Możesz również pobrać pełny tekst publikacji naukowej w formacie „.pdf” i przeczytać adnotację do pracy online, jeśli odpowiednie parametry są dostępne w metadanych.
Przeglądaj rozprawy doktorskie z różnych dziedzin i twórz odpowiednie bibliografie.
1
Quinton, Margaret. "Genetic diversity in selected populations". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0016/NQ47407.pdf.
Pełny tekst źródła
2
Barker, Gary L. A. "Genetic diversity in Emiliania huxleyi". Thesis, University of Bristol, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294614.
Pełny tekst źródła
3
Fitzcharles, Elaine M. "Genetic diversity of Antarctic fish". Thesis, University of St Andrews, 2015. http://hdl.handle.net/10023/6860.
Pełny tekst źródłaStreszczenie:
Correct species identification is fundamental to all areas of biology, but particularly the policy related areas of conservation and fisheries management. To enable guidelines to be developed for environmental management and conservation, such identifications need links to studies of the evolutionary history, biological factors and environmental influences driving species divergence and population dynamics for the target species. This study concerns two genera of gadiform fish, Muraenolepis and Macrourus, found in southern temperate and Antarctic waters, with a single species, Macrourus berglax, present in the North Atlantic. With similar distribution patterns to toothfish species, Dissostichus eleginoides and D. mawsoni, they are a major food source and by-catch of the toothfish fishery. Both are slow growing and long lived, with different evolutionary histories, life expectancies and strategies for reproduction. For both genera, the accuracy of morphological keys, number of described species and their distribution is under debate. This study has identified specimens to species level using both morphological and genetic techniques, redefining the range for morphological features and taxonomic keys. For Muraenolepis, this has clarified confusion over Mu. marmoratus and Mu. microps being a single species, confirmed some mis-identification from sexual dimorphism and provided genetic evidence for the recently described species Mu. evseenkoi. For Macrourus, this work has identified a new species, now named Ma. caml, and found that Ma. holotrachys and Ma. berglax are genetically identical, raising the question of bipolar distribution or recent divergence. The low level of genetic variation within both species suggests a recent evolution and expansion into Antarctic waters. Similar geographic species limits imply common processes influencing divergence, with the oceanographic fronts as potential barriers. Further investigation of niche overlap and fine scale population structure are required to fully understand the processes driving speciation and provide the underlying data required for fisheries management.
4
Olsson, Jenny. "Genetic diversity and hardiness in Scots pine from Scandinavia to Russia". Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-160222.
Pełny tekst źródłaStreszczenie:
The postglacial recolonization of northern Europe supposedly originated from Western Europe and the Russian Plain, however, recent molecular and macrofossil-based investigations suggest that the history may be more complex than previously thought. This study aims to investigate the genetic diversity and population structure of Scots pine from Scandinavia to Russia to re-evaluate its recolonization history, and to examine whether the pattern of spatial genetic diversity has any adaptive significance. Populations ranging from Norway to Russia were sampled and genotyped using genotyping-by-sequencing. The seedlings were freeze tested to provide an average degree of hardiness for every population. Eight hundred and thirty-two seedlings were analyzed, and 6,034 SNPs were recovered in these individuals after stringent filtering. Population structure was investigated using fastStructure and differentiation between populations was estimated with pairwise FST and analysis of molecular variance (AMOVA) to assess the genetic variability. Genetic diversity was measured as observed heterozygosity, H0, in populations, clusters and overall. Two genetic clusters were detected in the samples, one in Norway and Sweden and one in Russia. These clusters are weakly differentiated (FST = 0.01202) with only 0.66 % variation between them. Highest variation was found within populations (98.8 %) and the overall genetic diversity for all populations was high (Ho = 0.2573). The weak differentiation and high diversity are indicative of extensive gene flow between populations in this species. The composition of the clusters across the sampled area suggests a westward recolonization from the Russian Plain into Scandinavia, and a possible local origin of another polymorphism in Norway and Sweden. No clear relationship between cold hardiness and genetic variation was detected. The clinal variation in cold hardiness reflects local adaptation, and the difference between genetic and phenotypic variation is likely due to epigenetic regulation or polygenic inheritance. More extensive genome scan is needed to understand the genetic basis of local adaptation.
5
Thomson, Brent Robert. "Genetic Diversity in Wheat: Analysis using Diversity Arrays Technology (DArT) in bread and durum wheats". Thesis, The University of Sydney, 2011. http://hdl.handle.net/2123/8087.
Pełny tekst źródłaStreszczenie:
With increasing demands on the quality and quantity of food required now and in the future, improvements to current agriculture practices are required. Increased food production requires utilisation of more agricultural land, pushing crops into non- traditional areas. The need for advances in agricultural technologies are not only required for current crop varieties, but for new varieties with increased tolerance to environmental stresses. Technological improvement means better crop yields and reduced land, water, fertilizer and pesticide use. Diversity Arrays Technology (DArT) was used to study wheat diversity, specifically to identify polymorphic markers between various wheat cultivars for use in marker- assisted breeding programs. The hybridisation based technology was used to analyse various bread and durum wheat cultivars for increased understanding of genomic diversity. Analysis shows that DArT is able to discriminate between tissue samples from wheat cultivars grown under various environmental stresses with polymorphic markers identified between samples treated with differing salt, light and temperature conditions. Epigenetic diversity was analysed through methylation detection using DArT to identify a list of candidate polymorphic markers. Markers were identified using the methylation sensitive restriction enzyme McrBC to generate control and treated targets. Diversity through cultivar exploration, looking at breeding experiments between cultivars with phenotypic extremes to examine salt tolerance versus in-tolerance using DArT produced a recombinant inbred line genetic linkage map. Bulk segregant analysis was also used to group phenotypic samples. Candidate markers were identified between cultivars that can be used to genotyping tetraploid and hexaploid wheat cultivars for germplasm identification. In addition, the identification of trait-linked molecular markers, such as salt resistance, plant breeders can genotype individual plants and populations of cultivars to determine the most suitable cultivar to plant that best complements to its local environment. This eliminates the need for multiple planting cycles to optimize crop selections, and gives the plant breeder the highest possible chance for crop success (yield, quality, performance and cost).
6
Paul, Richard E. L. "The genetic diversity of Plasmodium falciparum". Thesis, University of Oxford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318788.
Pełny tekst źródła
7
Townsend, S. J. "Genetic diversity and domestication in sheep". Thesis, University of East Anglia, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368146.
Pełny tekst źródła
8
Williams, Louise Jane. "Recombinational mechanisms in human genetic diversity". Thesis, University of Nottingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342483.
Pełny tekst źródła
9
Rogers, Emma Jayne. "Haplotype evolution and human genetic diversity". Thesis, University of Nottingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342507.
Pełny tekst źródła
10
Ritz, Liliane R. "Genetic diversity in the tribe Bovini /". [S.l.] : [s.n.], 1997. http://www.ub.unibe.ch/content/bibliotheken_sammlungen/sondersammlungen/dissen_bestellformular/index_ger.html.
Pełny tekst źródła
11
Schmid, Marianne. "Genetic diversity in Swiss cattle breeds /". [S.l.] : [s.n.], 1998. http://www.stub.unibe.ch/html/haupt/datenbanken/diss/bestell.html.
Pełny tekst źródła
12
Ceccobelli, Simone. "Genetic diversity of mediterranean autochthonous chicken breeds". Doctoral thesis, Università degli studi di Padova, 2013. http://hdl.handle.net/11577/3422653.
Pełny tekst źródłaStreszczenie:
Local breeds can be considered a part of the history of some human populations as well as important materials from a scientific point of view. The characterisation and inventory of animal genetic resources and routine monitoring of population for variability are fundamental to breed improvement strategies and programmes and for conservation programmes. Molecular genetics provide us with very remarkable tools to analyse the variation between and within breeds. Different approaches have been developed to understand the different aspects that contribute to breed differentiation.
The thesis is made up in three contributes. The objective of the first part (Chapter 3) was to investigate genetic variation and to analyze population structure in two Italian breeds (Ancona and Livorno) as potential valuable genetic variability source. Blood samples from 131 individuals were collected and genotyped through a thirty microsatellites-based analysis. All the observed descriptive statistical indexes suggested a heterozygosity deficiency and an inbreeding level (mean observed heterozygosity = 0.46, mean expected heterozygosity = 0.53, FIS in Ancona and Livorno = 0.251 and 0.086). The tree from inter-individual DAS distance using Neighbour-Joining algorithm and the FCA analysis showed a higher internal variability in Livorno than in Ancona. STRUCTURE analysis showed the genetic uniqueness of the breeds and the presence of sub-groups in Ancona originating from a possible genetic isolation.
In Chapter 4, the genetic characterization of five Italian chicken breeds (Ancona, Livornese bianca, Modenese, Romagnola and Valdarnese bianca) was described, including their remote genetic origins, the differentiation among them and their present level of biodiversity. The first aim of this study is to investigate the maternal genetic origin of five Italian local chicken breeds based on mitochondrial DNA (mtDNA) information. The second topic was to assess the genetic diversity and population structure of these chicken breeds, and to quantify the genetic relationships among them by using 27 microsatellite markers. To achieve these targets, a 506 bp fragment of the D-loop region was sequenced in 50 chickens of the five breeds. Eighteen variable sites were observed which defined 12 haplotypes. They were assigned to three clades and probably two maternal lineages. Results indicated that 90% of the haplotypes are related to clade E, which has been described previously to originate from the Indian subcontinent. For the microsatellite analysis, 137 individual blood samples from of the five Italian breeds were collected. A total of 147 alleles were detected at 27 microsatellite loci. The five Italian breeds showed a slightly higher inbreeding index (FIS = 0.08) when compared to commercial populations used as reference. Structure analysis showed a separation of the Italian breeds from these reference populations; a further sub-clustering allowed to discriminate between the five Italian breeds.
Aim of the third study was to investigate the genetic diversity and relationship among sixteen Mediterranean chicken populations using sequencing mitochondrial DNA and a panel of 27 microsatellite markers (Chapter5). A 506 bp fragment of the mtDNA D-loop region was sequenced in 160 DNA samples. Twenty-five variable sites, that defined 21 haplotypes, were observed and assigned to three clades and probably three maternal lineages. The major haplotype (E1) was present in the Mediterranean populations, originates from the Indian subcontinent. Different sequences were included in haplogroup A and B that are distributed in South China and Japan. For the microsatellite analysis, 465 individual blood samples from of the sixteen Mediterranean chicken populations were collected. The results indicated that about 22% of the total variability originated from variation between the Mediterranean populations as previously reported in other European chicken breeds. Structure analysis exhibited extensive genetic admixture in many studied populations. In conclusion, suitable conservation measures should be implemented for these breeds in order to minimize inbreeding and uncontrolled crossbreeding. A special care is required for the conservation and preservation of these potentially vulnerable breeds.Le razze locali possono essere considerate parte della storia di molte popolazioni umane, così come materiale importante dal punto di vista scientifico. La catalogazione, la caratterizzazione e il controllo di routine della variabilità delle risorse genetiche animali sono pratiche fondamentali nelle strategie di miglioramento genetico e nei programmi di conservazione. La genetica molecolare ci fornisce importanti strumenti per analizzare la variabilità genetica tra e all’interno delle razze. Numerosi approcci sono stati sviluppati e utilizzati per comprendere i diversi aspetti che contribuiscono alla differenziazione delle razze. Questa tesi è costituita da tre contributi scientifici. L’obiettivo del primo (Capitolo 3) è stato quello di studiare la variabilità e analizzare la struttura di popolazione di due razze avicole Italiane (Ancona e Livorno), poiché possono essere considerate una fonte preziosa di variabilità genetica. Sono stati raccolti campioni di sangue da 131 animali e genotipati mediante l’utilizzo di un panel di 30 marcatori microsatelliti. Gli indici genetici calcolati suggeriscono un deficit di eterozigosità e un certo livello di consanguineità (eterozigosità media osservata = 0,46; eterozigosità media attesa = 0,53; FIS in Ancona e Livorno = 0,251 e 0,086). L’albero delle distance inter-individuali DAS, elaborato mediante l’algoritmo Neighbour-Jouning, e l’analisi FCA, hanno evidenziato una elevata variabilità interna in Livorno rispetto alla razza Ancona. L’analisi mediante il software STRUCTURE ha evidenziato l’unicità genetica delle due razze oggetto di studio e la presenza di subgruppi nella razza Ancona, derivanti da un possibile isolamento genetico. Nel quarto capitolo, è descritta la caratterizzazione genetica di cinque razze avicole italiane (Ancona, Livornese bianca, Modenese, Romagnola e Valdarnese Bianca), incluse le loro origini, la loro differenziazione e il loro attuale livello di variabilità genetica. Il primo obiettivo di tale studio è di indagare l’origine genetica di queste cinque razze di pollo italiane sulla base delle informazioni provenienti dal DNA mitocondriale (mtDNA). Il secondo obiettivo è stato quello di valutare la variabilità genetica, la struttura di popolazione e le loro relazioni genetiche mediante l’utilizzo di 27 marcatori molecolari microsatelliti. Al fine di raggiungere tali obiettivi, è stato sequenziato un frammento di 506 bp della regione D-loop del DNA mitocondriale di 50 animali delle cinque razze avicole oggetto di studio. Sono stati individuati diciotto siti di variabilità che hanno definito 12 aplotipi. Questi ultimi sono stati assegnati a tre aplogruppi, probabilmente attribuiti a due linee materne. I risultati hanno mostrato che il 90% degli aplotipi ricade nell’aplogruppo E, originario del subcontinente Indiano come descritto in precedenza da altri autori. Per l’analisi microsatellitare, 137 singoli campioni di sangue sono stati raccolti nelle cinque razze italiane oggetto di studio. Un totale di 147 alleli è stato rilevato in 27 marcatori microsatelliti. Le cinque razze Italiane hanno mostrato un livello di consanguineità leggermente superiore (FIS = 0,08) rispetto alle popolazioni commerciali utilizzate come razze di riferimento. L’analisi con il software STRUCTURE ha rilevato una chiara separazione delle cinque razze Italiane da queste popolazioni riferimento; una seconda analisi delle sole razze oggetto di studio ha permesso di discriminare le singole razze italiane. Scopo del terzo studio è stato quello di descrivere la variabilità genetica e le relazioni tra sedici popolazioni avicole allevate nel bacino del Mediterraneo, mediante il sequenziamento della regione D-loop del DNA mitocondriale e l’utilizzo di un panel di 27 marcatori molecolari microsatelliti (Capitolo 5). Un frammento di 506 bp del D-loop mitocondriale è stato sequenziato in 160 campioni di DNA. Sono stati osservati 25 siti di variabilità e 21 aplotipi che definiscono tre aplogruppi e probabilmente tre linee materne. Il principale aplotipo, individuato nelle popolazioni del Mediterraneo, è rappresentato dall’E1 derivante dal subcontinente Indiano. Altre sequenze sono incluse negli aplogruppi A e B, i quali originano dal sud della Cina e dal Giappone. Per l’analisi microsatellitare, sono stai racconti 465 campioni di sangue. I risultati indicano che circa il 22% della variabilità totale origina da variazioni che intercorrono tra le popolazioni oggetto di studio. L’analisi di STRUCTURE ha rilevato un’ampia mescolanza genetica in molte delle popolazioni studiate. In conclusione, adeguate misure di conservazione dovrebbero essere attuate al fine di minimizzare fenomeni di consanguineità e d’incrocio incontrollato nelle razze studiate. Particolare attenzione, pertanto, è richiesta al fine di conservare e salvaguardare queste razze potenzialmente vulnerabili.
13
Gardner, Michelle. "Genetic diversity of " brain genes" across worldwide". Doctoral thesis, Universitat Pompeu Fabra, 2007. http://hdl.handle.net/10803/7169.
Pełny tekst źródłaStreszczenie:
El treball presentat en aquesta tesi és un estudi de la diversitat genètica en un conjunt de gens implicats en funcions neurològiques ("Gens cerebrals"). Hom ha examinat vint-i-dos gens implicats en els sistemes de neurotransmissió dopaminèrgic, serotoninèrgic i glutamatèrgic.L'objectiu de l'estudi té dos vessants: per una banda l'anàlisi de la diversitat genètica en un conjunt de gens implicats en malaltia humana, en aquest cas en malaltia psiquiàtrica, en poblacions humanes mundials, amb la intenció d'assentar les bases per propers esforços de mapatge genètic; i per altra banda analitzar la diversitat genètica en aquest conjunt de gens per tal de descobrir evidències d'esdeveniments històrics, incloent possibles evidències de selecció.
The work presented in this thesis is a study of the genetic variation in a set of genes related to neurological function ('Brain genes'). Twenty two genes are examined, all of which are involved in either the Dopaminergic, Serotonergic or the Glutamatergic systems of neurotransmission.
The objective of the study has two aspects: on the one hand the analysis of genetic variation in a set of genes which are implicated in human disease, in this case psychiatric disease, across global human populations, towards the end of providing some new insight for gene mapping efforts, and on the other hand the study of genetic variation in this set of genes may reveal traces of the population history events undergone, including possible evidence for selection.
14
Wilkinson, Samantha. "Genetic diversity and structure of livestock breeds". Thesis, University of Edinburgh, 2012. http://hdl.handle.net/1842/6488.
Pełny tekst źródłaStreszczenie:
This thesis addresses the genetic characterisation of livestock breeds, a key aspect of the long-term future breed preservation and, thus, of primary interest for animal breeders and management in the industry. First, the genetic diversity and structure of breeds were investigated. The application of individual-based population genetic approaches at characterising genetic structure was assessed using the British pig breeds. All approaches, except for Principle Component Analysis (PCA), found that the breeds were distinct genetic populations. Bayesian genotypic clustering tools agreed that breeds had little individual genetic admixture. However, inconsistent results were observed between the Bayesian methods. Primarily, BAPS detected finer genetic differentiation than other approaches, producing biologically credible genetic populations. BAPS also detected substructure in the British Meishan, consistent with prior known population information. In contrast, STRUCTURE detected substructure in the British Saddleback breed that could not wholly be explained. Further analysis of the British Saddleback revealed that the genetic subdivision did not reflect its historical origin (union of Essex pig and Wessex Saddleback) but was associated with herds. The Rainbarrow appeared to be moderately differentiated from the other herds, and relatively lower allelic diversity and higher individual inbreeding, a possible result of certain breeding strategies. The genetic structure and diversity of the British traditional chicken breeds was also characterised. The breeds were found to be highly distinctive populations with moderately high levels of within-breed genetic diversity. However, majority of the breeds had an observed heterozygote deficit. Although individuals clustered to their origin for some of the breeds, genetic subdivision of individuals was observed in some breeds. For two breeds the inferred genetic subpopulations were associated with morphological varieties, but in others they were associated with flock supplier. As with the British Saddleback breed, gene flow between flocks within the chicken breeds should be enhanced to maintain current levels of genetic diversity. Second, the thesis focused on breed identification through the assignment of individuals to breed origin. Dense genome-wide assays provide an opportunity to develop tailor-made panels for food authentication, especially for verifying traditional breed-labelled products. In European cattle breeds, the prior selection of informative markers produced higher correct individual identification than panels of randomly selected markers. Selecting breed informative markers was more powerful using delta (allele frequency difference) and Wright's FST (allele frequency variation), than PCA. However, no further gain in power of assignment was achieved by sampling in excess of 200 markers. The power of assignment and number of markers required was dependent on the levels of breed genetic distinctiveness. Use of dense genome-wide assays and marker selection was further assessed in the British pig breeds. With delta, it was found that 96 informative SNP markers were sufficient for breed differentiation, with the exception of Landrace and Welsh pair. Assignment of individuals to breed origin was high and few individuals were falsely assigned, especially for the traditional breeds. The probability that a sample of a presumed origin actually originated from that breed was high in the traditional breeds. Validation of the 96-SNP panel using independent test samples of known origin and market samples revealed a high level of breed label conformity.
15
Gustafson, Steven Matt. "An analysis of diversity in genetic programming". Thesis, University of Nottingham, 2004. http://eprints.nottingham.ac.uk/10057/.
Pełny tekst źródłaStreszczenie:
Genetic programming is a metaheuristic search method that uses a population of variable-length computer programs and a search strategy based on biological evolution. The idea of automatic programming has long been a goal of artificial intelligence, and genetic programming presents an intuitive method for automatically evolving programs. However, this method is not without some potential drawbacks. Search using procedural representations can be complex and inefficient. In addition, variable sized solutions can become unnecessarily large and difficult to interpret. The goal of this thesis is to understand the dynamics of genetic programming that encourages efficient and effective search. Toward this goal, the research focuses on an important property of genetic programming search: the population. The population is related to many key aspects of the genetic programming algorithm. In this programme of research, diversity is used to describe and analyse populations and their effect on search. A series of empirical investigations are carried out to better understand the genetic programming algorithm. The research begins by studying the relationship between diversity and search. The effect of increased population diversity and a metaphor of search are then examined. This is followed by an investigation into the phenomenon of increased solution size and problem difficulty. The research concludes by examining the role of diverse individuals, particularly the ability of diverse individuals to affect the search process and ways of improving the genetic programming algorithm. This thesis makes the following contributions: (1) An analysis shows the complexity of the issues of diversity and the relationship between diversity and fitness, (2) The genetic programming search process is characterised by using the concept of genetic lineages and the sampling of structures and behaviours, (3) A causal model of the varied rates of solution size increase is presented, (4) A new, tunable problem demonstrates the contribution of different population members during search, and (5) An island model is proposed to improve the search by speciating dissimilar individuals into better-suited environments. Currently, genetic programming is applied to a wide range of problems under many varied contexts. From artificial intelligence to operations research, the results presented in this thesis will benefit population-based search methods, methods based on the concepts of evolution and search methods using variable-length representations.
16
Clarke, Stephen James. "Genetic diversity in nativeIrish oak and ash". Thesis, Queen's University Belfast, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.397902.
Pełny tekst źródła
17
Mauricio, Isabel Larguinho. "Genetic diversity in the Leishmania donovani complex". Thesis, London School of Hygiene and Tropical Medicine (University of London), 2000. http://researchonline.lshtm.ac.uk/682281/.
Pełny tekst źródłaStreszczenie:
The Leishmania donovani complex comprises four described species: L. donovani, L. archibaldi, L. infantum and L. chagasi. L. chagasi is the only New World species and has been considered similar to L. infantum, although some authors insist on maintenance of its independent species status. L. donovani has at least two major epidemiological subgroups whose relationships are poorly understood. In this thesis, molecular biological techniques were used to investigate the taxonomy and phylogenetic relationships within the L. donovani complex, with isoenzyme analysis (lEA) as reference technique. Random amplification of polymorphic DNA (RAPD) was used to provide anonymous genetic markers which allowed overall comparisons of genomes. Selected target genes and intergenic regions were also amplified by the polymerase chain reaction (PCR), namely the major surface protease (msp or gp63), the mini-exon and the ribosomal internal transcribed spacer (ITS). PCR products of intergenic regions between msp genes (ITG/CS and ITG/L), mini-exon and ITS were analysed by restriction fragment length polymorphism (RFLP). Phylogenies generated from each of the methods were compared with that of IEA. L. infantum and L. chagasi were found to be synonymous, whilst L. donovani was found to be more polymorphic than L. infantum and a fourth possible species in the complex, L. archibaldi, was not supported. Six genetic groups of strains were identified in the L. donovani complex, based on all DNA based analyses, which agreed with IEA typing. Pooled data from RFLP and RAPD analyses generated robust phylogenies which were congruent with ITG/CS RFLP and msp DNA sequence based phylogenies, but not with lEA phylogenies. The evolutionary history of the L. donovani complex is analysed in the light of the present results. The diverse typing methods were also evaluated and genetic markers suggested, that are applicable to classification and typing of L. donovani species and strains.
18
Soto, Esteban. "Genetic and virulence diversity of Flavobacterium columnare". Master's thesis, Mississippi State : Mississippi State University, 2007. http://library.msstate.edu/etd/show.asp?etd=etd-05292007-091752.
Pełny tekst źródła
19
Palo, Jukka. "Genetic diversity and phylogeography of landlocked seals". Helsinki : University of Helsinki, 2003. http://ethesis.helsinki.fi/julkaisut/mat/ekolo/vk/palo/.
Pełny tekst źródła
20
Koban, Evren. "Genetic Diversity Of Native And Crossbreed Sheep Breeds In Anatolia". Phd thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605694/index.pdf.
Pełny tekst źródłaStreszczenie:
In this study the genetic diversity in Turkish native sheep breeds was investigated based on microsatellite DNA loci. In total, 423 samples from 11 native and crossbreed Turkish sheep breeds (Akkaraman, Morkaraman, Kivircik, ivesi, Dagliç, Karayaka, HemSin, Norduz, Kangal, Konya Merinosu, Tü
rkgeldi) and one Iraqi breed (Hamdani) were analyzed by sampling from breeding farms and local breeders. After excluding close relatives by Kinship analysis, the genetic variation within breeds was estimated as gene diversities (HE), which ranged between 0.686 and 0.793. The mean number of observed alleles (MNA) ranged between 5.8 and 11.8. The allele frequency distribution across Turkey showed no gradient from east to west expected in accordance with the Neolithic Demic Diffusion model. The differentiation between different samples of Akkaraman, Dagliç
and Karayaka breeds was tested by FST index. Akkaraman1 sample from the breeding farm was significantly (P<
0.001) different from the other two Akkaraman samples. Deviation from HW expectations observed for Akkaraman1, ivesi, Morkaraman and HemSin breeds. AMOVA analysis revealed that most of the total genetic variation (~90%) was partitioned within the individuals. In parallel to this observation, when factorial correspondence analysis and shared alleles distances were used to analyze the relationship between the individuals of the breeds, there was no clear discrimination between breeds. Moreover, NJ tree constructed based on DA genetic distance, and PC analyses were used to analyze among breed differentiation. Delaunay Network drew 4 genetic boundaries (two of them being parallel to geographic boundaries) between breeds. All the results indicated that Kivircik was the most differentiated breed. Finally, Mantel Test and Bottleneck analysis did not reveal a significant result. Kivircik breed, among all native Turkish breeds, was found to be the genetically closest to the European breeds based on the loci analyzed. The genetic variation in Turkish breeds was not much higher than that of European breeds, which might be a consequence of the recent sharp decrease in sheep number.
21
Lee, Suk-wah, i 李淑華. "Fungicide resistance and genetic diversity of Penicillium digitatum inHong Kong". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B31226255.
Pełny tekst źródła
22
Moody, Jonathan. "Genetic diversity in the processing and transcriptomic diversity in the targeting of microRNAs". Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/25409.
Pełny tekst źródłaStreszczenie:
MicroRNAs are short RNA molecules that are central to the regulation of many cellular and developmental pathways. They are processed in several stages from structured precursors in the nucleus, into mature microRNAs in the cytoplasm where they direct protein complexes to regulate gene expression through, often imperfect base-pairing with target messenger RNAs. The broad aim of this project is to better understand how polymorphisms and new mutations can disrupt microRNA processing and targeting, and ultimately define their contributions to human disease. I have taken two approaches towards this. The first approach is to comprehensively identify the microRNA targets by developing and applying a novel computational pipeline to identify microRNA binding events genome-wide in RNA-RNA interaction datasets. I use this to examine the transcriptomic diversity of microRNA binding, finding microRNA binding events along the full length of protein coding transcripts and with a variety of non-coding RNAs. This reveals enrichment for non-canonical microRNA binding at promoters and intronic regions around splice sites, and identifies highly spatially clustered binding sites within transcripts that may be acting as competitive endogenous RNAs to compete for microRNAs, effectively sequestering them. Using statistical models and new cell fractionated RNA-seq data, I rank the features of microRNAs and their binding sites which contribute to the strength and specificity of their interaction to provide a better understanding of the major determinants of microRNA targeting. The second approach is to directly identify DNA sequence changes in microRNA precursors that alter processing efficiency affecting mature microRNA abundance which are routinely overlooked in the search for disease or trait associated causal variants. I have systematically screened public datasets for both rare and common polymorphisms that overlap microRNA precursors and are correlated with mature microRNA levels as measured in short RNA sequencing. I use these eQTL SNPs to examine the most important microRNA precursor regions and sequence motifs. Several of these SNPs have been observed as risk factors in cancer or other clinically relevant traits, and correlated with microRNA processing efficiency. I demonstrate that a specific DNA change which is known to be important in the development of some cancers, is located in a microRNA precursor and affects the balance of its two products, miR-146a-3p and miR-146a-5p, that can be produced from that single precursor providing new insights into the mechanisms of microRNA production and the aspects of genetic mis-regulation that result in cancer. I find further examples of common human polymorphisms that appear to affect microRNA production from their precursors, several of these variants are independently implicated in human immune disease, cancer susceptibility and associated with other complex traits. As they exhibit a molecular phenotype and immediately lead to mechanistic hypotheses of trait causality that can be tested, these variants could provide a route into the frequently intractable problem of mechanistically linking non-coding genetic variation to human phenotypes. Applying similar studies to patient DNA has revealed rare and unique DNA changes that are now candidates for causing human disease that are being subject to follow-up experimental studies. Collectively this work has started to define which sequences changes in microRNAs are likely to disrupt their function and provides a paradigm for the analysis of microRNA sequence variants in human genetic disease.
23
Wint, Ashley A. "Genetic Diversity in Native and Invasive Rubus (Rosaceae)". TopSCHOLAR®, 2008. http://digitalcommons.wku.edu/theses/17.
Pełny tekst źródłaStreszczenie:
Invasive species are an increasing threat to biological diversity as well as a leading cause of recent species’ extinctions. Invasives spread quickly and efficiently, and the U.S spends millions of dollars annually in the control and eradication of these species. More information is necessary in order to predict which species may become invasive. Rubus (Rosaceae) was chosen for study because this genus includes various ploidy levels, reproductive modes, and species that are invasive as well as native.
Three Rubus species were chosen to represent apomictic and tetraploid invasives (Rubus armeniacus), a sexual and diploid native species (R. occidentalis), and a sexual and diploid invasive species (R. phoenicolasius). Specimens were collected across the U.S. and two different genetic fingerprinting techniques were used; Amplified Fragment Length Polymorphism (AFLP) and Randomly Amplified Fingerprints (RAF).
Using three AFLP primers and two RAF primers, genetic similarity was determined and phylograms were constructed. Through statistical analysis and phylogram data it was determined that there might be slightly more genetic diversity in native R. occidentalis than in invasive R. phoenicolasius. Genetic diversity between apomictic and tetraploid Rubus armeniacus and the two sexual and diploid Rubus species were so similar that no distinction could be made, although the mean pairwise distances and mean number of alleles were significantly different. It was also found that geographic distance and genetic similarity do not appear to be related in these three Rubus species. During the course of this study it was also observed that the AFLP technique produced more alleles than the RAF technique, although this difference was not significant.
24
Graham, Elaine Brigid. "Genetic diversity and crossing relationships of Lycopersicon chilense /". For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2005. http://uclibs.org/PID/11984.
Pełny tekst źródła
25
Larsson, Pär. "The genetic composition and diversity of Francisella tularensis". Doctoral thesis, Umeå University, Clinical Microbiology, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-1139.
Pełny tekst źródłaStreszczenie:
Francisella tularensis is the causative agent of the debilitating, sometimes fatal zoonotic disease tularemia. To date, little information has been available on the genetic makeup of this pathogen, its evolution, and the genetic differences which characterize subspecific lineages. These are the main areas addressed in this thesis.
The work indicated a high degree of genetic conservation of F. tularensis, both on the sequence level as determined by sequencing and on the compositional level, determined by array-based comparative genomic hybridizations (aCGH). One striking finding was that subsp. mediasiatica was most similar to subsp. tularensis, despite their natural confinement to Central Asia and North America, respectively. All genetic Regions of Difference RD found by aCGH distinguishing lineages were had resulted from repeat-mediated excision of DNA. This was used to identify additional RDs. Such data along with a multiple locus sequence analysis suggested an evolutionary scenario for F. tularensis.
Based on genomic information, a novel typing scheme for F. tularensis was furthermore devised and evaluated. This method provided increased robustness compared to previously used methods for F. tularensis typing, while retaining a capacity for high resolution.
Finally, the genomic sequence of the highly virulent F. tularensis strain SCHU S4 was determined and analysed. Evidenced by numerous pseudogenes and disrupted metabolic pathways, the bacterium appears to be undergoing a genome reduction process whereby a large proportion of the genetic capacity gradually is lost. It is likely that F. tularensis has irreversibly has evolved into an obligate host-dependent bacterium, incapable of a free-living existence. Unexpectedly, the bacterium was found to be devoid of common virulence mechanisms such as classic toxins, or type III and IV secretion systems. Instead, the virulence of this bacterium is probably largely the result of specific and unusual mechanisms.
26
Uimaniemi, L. (Leena). "Maintenance of genetic diversity in four taiga specialists". Doctoral thesis, University of Oulu, 2004. http://urn.fi/urn:isbn:9514274105.
Pełny tekst źródłaStreszczenie:
Abstract
Genetic diversity in three taiga specialists – the Siberian
tit (Parus cinctus), the Siberian jay
(Perisoreus infaustus) and the Siberian flying
squirrel (Pteromys volans) – was assessed by
comparing DNA sequence variation across the mitochondrial control region
and allele frequencies of microsatellites from samples collected from
Fennoscandia and Siberia. Population sizes of these species have
declined in association with fragmentation and loss of suitable forest
habitat due to modern forestry practices in Fennoscandia. The red
squirrel (Sciurus vulgaris) served as a reference
for the flying squirrel.
Genetic differentiation among species studied ranged from a
panmictic population in the Siberian tit to that of the strong
differentiation of populations
(θST = 53%) in the flying squirrel
in Finland. MtDNA and microsatellite data, together with assignment
studies, showed the Siberian jay population to be significantly
genetically structured and supported the existence of a metapopulation
like structuring in Fennoscandia. Division of genetic variation among
flying squirrel populations along the ancient shoreline of the Littorina
Lymnea Sea stage of the Baltic Sea (7000 BP) and two geographically
associated branches in the minimum spanning network supported a two-way
colonisation history for the species. The Finnish inland appears to have
been colonised from the east in association with the arrival of Norway
spruce. At the same time, Coastal Finland was colonised from the
south-east through the Karelian Isthmus. Gene flow of the species
appeared female biased and restricted. Species exhibiting more
restrictive dispersal characteristics and habitat requirements possessed
stronger population genetic structure than those with opposite
characteristics.
Growth or contractions in population size leave characteristic
signatures in mtDNA that can be studied by comparing different sequence
diversity estimates among populations. I applied this method to the
species studied. Significant differences in nucleotide diversities
indicated restrictions in gene flow among populations in all species
studied. Half of the Siberian jay populations gave a signal of
population size bottleneck.
All the species studied showed differences in their population
genetic structures across their entire distribution ranges consistent
with the multirefugia model, most likely to be attributable to
differences in their ecological characteristics and Pleistocene
histories.
27
Larsson, Pär. "The genetic composition and diversity of Francisella tularensis /". Umeå : Umeå universitet, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-1139.
Pełny tekst źródła
28
Ismail, Mohamed. "Molecular genetic diversity among natural populations of Populus". Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/26273.
Pełny tekst źródłaStreszczenie:
Genetic diversity is a key factor in species survival, evolution, and adaptation. It also reveals species genetic structure and provides insights into how different demographic forces shape species genetic variability. Although, black cottonwood (Populus trichocarpa Torr. & Gray) is the first tree to have its genome completely sequenced; however, information regarding its natural genetic diversity and population structure is lacking. I have investigated the extent of genetic diversity within and among 38 natural populations of P. trichocarpa sampled across British Columbia using 10 nuclear (nuSSR) and 12 chloroplast microsatellite (cpSSR) markers.
CpSSR represents two haplotypes, clustering as northern and southern groups; however, a
Bayesian population structure analysis suggested the presence of three highly admixed groups supported by low population differentiation (low FST and RST). Monmonier’s spatial analysis suggested the presence of one genetic discontinuity dividing the studied area into northern and southern regions. These findings indicated that P. trichocarpa might have originated from two, northern and southern, glacial refugia that have experienced moderate contact through extensive gene flow. Nucleotide diversity for 10 candidate-gene loci involved in adaptive, defence, and housekeeping functions was abundant and varied across loci, with the majority showing neutral variations. Linkage disequilibrium (LD), decays rapidly to r² ≈ 0.18 within 700 base pairs (bp).
Comparing the nucleotide diversity between P. trichocarpa and P. balsamifera L. to the Eurasian
P. tremula L. indicated that the two North American species had lower diversity (θw range 0.002 to 0.004) than the Eurasian poplar (θw = 0.005). The estimated time of divergence between the two North American and the Eurasian species indicated that the latter was five- to six-fold older compared to the two former species. The substitution rate was lower in North American species
(0.4 x 10-⁸ per year) compared to the Eurasian poplar (2 x 10-⁸). Different association genetics models produced strikingly different results after the inclusion or exclusion of population structure, highlighting the importance of proper model construction.
29
May, Shoshanna. "Fitness and genetic diversity in Bufo calamita populations". Thesis, University of Sussex, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.505908.
Pełny tekst źródłaStreszczenie:
The aims of this DPhil were the characterisation of major histocompatibility complex class II β loci in the amphibian species Bufo calamita, determination of fitness of four Bufo calamita populations and measurement of genetic diversity at both microsatellite loci and MHC class II β loci. The genetic diversity at microsatellite loci is considered to be neutral to selection and the genetic diversity seen at MHC loci is adaptive. Fitness in the four populations was measured using the known larval fitness traits age at metamorphosis, growth rates and survival. A 114 base pair section of MHC class II loci was characterised in this study. It was shown here that the diversity at neutral microsatellite markers was negatively correlated with adaptive MHC class II variation. No correlation was found between microsatellite HE and the larval fitness traits growth rate, survival and age at metamorphosis. However, MHC class II diversity was found to be associated with survival, and individuals that were heterozygous at both MHC loci had a significantly higher chance of survival than individuals homozygous at one or both of the two loci. A separate part of this DPhil project was the population genetics of six Irish Bufo calamita populations. The genetic structure was investigated using nine polymorphic microsatellite markers. It was found that all populations had similar and moderate levels of genetic diversity, comparable with those on the coast of north-west England. Toad populations were substantially differentiated, implying little migration between sites within historical times. Phylogenetics and estimates of divergence times supported the hypothesis that populations on the north coast of Dingle separated from those around Castlemaine Harbour many thousands of years ago, and are not recent introductions.
30
Craven, Kelly D. "COEVOLUTION AND GENETIC DIVERSITY IN GRASS-ENDOPHYTE SYMBIOSES". UKnowledge, 2003. http://uknowledge.uky.edu/gradschool_diss/431.
Pełny tekst źródłaStreszczenie:
Symbioses between cool-season grasses (Subfamily Pooideae) and endophytic fungi in the genera Epichlo and Neotyphodium straddle a continuum of interactions from antagonistic to highly mutualistic. Although these two genera of endophytes are closely related, Neotyphodium endophytes are strictly seed-transmitted and provide many physiological and defensive benefits to their hosts, while Epichlo spp. have an obligately sexual contagious stage wherein host inflorescences are replaced by fungal sexual structures (stromata), effectively sterilizing the plant. Between these two extremes of interactions are Epichlo spp. with a mixed strategy, where some grass tillers are sterilized while others develop normally and yield healthy endophyte-infected seeds. These symbioses offer a unique opportunity to dissect evolutionary mechanisms that may drive movement along this continuum. The research presented characterizes distinct hybridization processes in endophytes and grasses that result in the generation of astounding genetic diversity for the symbiosis. Interspecific hybridization via hyphal anatomosis is a common feature of Neotyphodium endophytes, and may promote mutualism by combining suites of defensive alkaloid genes and ameliorating the adverse evolutionary effects of an asexual lifestyle. My results demonstrate that several genetically distinct hybrid endophytes infect grass species in tribe Poeae. Further, I show that a highly mutualistic asexual endophyte infecting tall fescue (=Festuca arundinaceum Schreb.), Neotyphodium coenophialum, also infects two closely related and interfertile relatives of this host. My findings suggest that this seed-borne endophyte may have been introgressed into these grasses through sexual grass hybridization events. These findings highlight interspecific hybridization as a means of generating tremendous genetic variability in both endophytes and their hosts, thus magnifying the adaptive evolutionary potential of these symbioses. Further, I establish a phylogenetic framework for grasses naturally harboring Epichlo and Neotyphodium endophytes. I show that patterns of genetic divergence among grass lineages are emulated by those of their fungal symbionts. These results suggest that endophytes have co-evolved with grasses in subfamily Pooideae, and may have played a critical role in the evolutionary success and radiation of this group of grasses.
31
Cooper, Fiona Mary Phillips. "Geographic distribution and genetic diversity of black poplar". Thesis, University of Nottingham, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246878.
Pełny tekst źródła
32
Massawe, Festo J. "Phenotypic and genetic diversity in Bambara groundnut landraces". Thesis, University of Nottingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342048.
Pełny tekst źródła
33
Ward-Rainey, Naomi Louise. "Genetic diversity in members of the order Planctomycetales". Thesis, University of Warwick, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390026.
Pełny tekst źródła
34
Savage, Anne Margaret. "Genetic diversity and photosynthetic characteristics of zooxanthellae (Symbiodinium)". Thesis, University of York, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369298.
Pełny tekst źródła
35
Harris, Kathryn Ann. "Genetic diversity and evolution of hepatitis C virus". Thesis, Open University, 2000. http://oro.open.ac.uk/58053/.
Pełny tekst źródłaStreszczenie:
Inter- and intra-host Hey variation was investigated. First. a polymerase chain reactionrestriction fragment length polymorphism procedure was used to assign genotypes and subtypes to Hey infecting 567 individuals (comprising haemophilia patients, blood donors, intravenous drug users, attenders of antenatal and genito-urinary medicine clinics and chronic liver disease patients) from England and Wales. The majority of infections were associated with types 3a, 1 a and 1 b, and genotype distributions were generally similar in different sub-populations. Only 1 % of individuals were identified as being infected with more than one subtype. The intra-host variability of Hey in a selection of haemophilia patients, blood donors and intravenous drug users was then studied. For each individual, peR clones derived from the NS5b and 5' non-coding regions of the Hey genome were screened for sequence differences by denaturing gradient gel electrophoresis (DGGE) and nucleotide sequencing. The complexity and diversity of Hey quasi species, though differing between individuals, could not be correlated with the risk group to which the study patients belonged. Furthermore, no mixed genotype or subtype infections were identified. Thus the hypothesis that multiply exposed individuals are infected with a greater variety of HCY variants could not be substantiated. The DGGE procedure was further used to investigate the hypothesis that HCY genetic evolution occurs uniformly in patients during the acute phase of infection. Changes in diversity in the HCY hypervariable region 1 in individuals undergoing seroconversion were observed to differ between patients, thereby negating that hypothesis. Moreover, in a given individual, Hey could be subjected to either positive or negative selective pressure. Thus, factors other than the acute-phase host response determine the course of Hey genetic evolution.
36
Yang, N. "Population history and genetic diversity in the Americas". Thesis, University College London (University of London), 2010. http://discovery.ucl.ac.uk/668017/.
Pełny tekst źródłaStreszczenie:
This thesis aims to provide insights into the evolutionary history of populations from the Americas by studying patterns of genetic diversity in uniparental (Y-chromosome and mtDNA) and in biparental (X-chromosome and autosomes) marker systems in Native Americans and in populations of mixed ancestry (i.e. “Mestizos”) from Latin American countries. A novel aspect of this work, relative to previous studies, is that the same population samples were examined for all marker systems, thus allowing a more direct contrast of results obtained with the different markers used. I obtained in the laboratory the complete D-loop sequences (~1,200 bp) of 327 Native American mtDNAs from 22 populations sampled across the Americas and in 211 Mestizo individuals from 13 urban centres. I also genotyped 3 SNPs and 11 microsatellites on the Y-chromosome for 220 male individuals available. These data were analyzed together with unpublished data for 38 X-chromosome and 6 Y-chromosome STRs (collected by the Marshfield Foundation, USA) and with published data for 678 autosomal STRs obtained in the same population samples (Wang et al. 2007). Both, the Native and Mestizo populations show evidence of higher admixture with the Y-chromosome than with the mtDNA data. This indicates that admixture in these populations has been sex-biased and involved predominantly Native American women and immigrant men. This sex-biased admixture has thus influenced in a similar way the genetic makeup of both Native and Mestizo populations, which differ only in the extent of this admixture. Population structure analysis also indicates that the mtDNA lineages found in the Mestizo are of local origin, confirming the earlier proposal of a regional “genetic continuity” between Mestizo and native populations. This means that the Mestizo can, to some extent, allow the analysis of Native populations that do not exist anymore. For subsequent analyses I therefore considered the Native American mtDNA and Y-chromosome lineages identified in Mestizo populations as samples of from these presently unavailable native populations. These data demonstrate a lower diversity and higher differentiation among American populations, relative to other continental populations. In addition, a pattern of North to South decrease in population diversity (and increasing population differentiation) is observed across the American continent. These findings agree with the proposal that Native American ancestors came to the New World through the Bering Strait. These data also point to an important role of the coasts as facilitators of migration during the initial colonization of the continent. Phylogenetic, genetic structure and principal component analyses are broadly consistent with the geographic distribution of the populations examined and their proposed linguistic affinity. In addition, these data point to a differentiated demographic history between the various populations examined. Signals of population expansion were detected in the Meso American and Andean populations while populations from East and North West South American appear to have undergone population contractions.
37
Alves, Mara Lisa. "Exploring maize genetic diversity – a quality-driven perspective". Doctoral thesis, Universidade Nova de Lisboa, Instituto de Tecnologia Química e Biológica António Xavier, 2018. http://hdl.handle.net/10362/78960.
Pełny tekst źródłaStreszczenie:
"In Portugal, and to a certain extent, farmers keep growing traditional maize populations known for their bread quality, conserving simultaneously their high genetic diversity. Maize populations, genetically more heterogeneous than commercial hybrid varieties, can evolve and better adapt to a changing broader range of edaphic-climatic conditions. Unfortunately, these maize populations suffer from a real risk of disappearing, due to their characteristic low yields. It is, therefore, desirable to improve their agronomic performance while maintaining their valuable diversity levels.(...)"N/A
38
Tobar, Pinon Maria Gabriela. "Genetic Diversity of the Guatemalan Climbing Bean Collections". Thesis, North Dakota State University, 2017. https://hdl.handle.net/10365/28447.
Pełny tekst źródłaStreszczenie:
Since common bean is the most important legume crop for human consumption around the world, bean breeders are challenged to increase production of beans while facing new problems like climate change. Guatemalan climbing beans have been suggested to represent race Guatemala, a newly identified race in the Middle American gene pool that may represent an untapped source of alleles for bean improvement. This study confirmed the existence of race Guatemala in the Middle American gene pool and its differentiation from other races. The low population structure found within these Guatemalan beans also makes this population ideal for discovery of candidate genes for important traits. We demonstrate that the Guatemalan population was useful to provide candidate genes for previously reported genetic factors like the V gene for flower color, and the Asp gene for seed coat luster. The important relationship between flowering time and altitudinal adaptation of beans was also emphasized.USAID
Legume Innovation Lab Project
North Dakota State University (NDSU)
ICTA
39
Gutiérrez, Lucía. "Genetic diversity in cultivated and wild Hordeum species". [Ames, Iowa : Iowa State University], 2008.
Znajdź pełny tekst źródła
40
Willey, N. J. "Rust Resistance in Wheat-Diversity and Genetic Studies". Thesis, The University of Sydney, 2011. https://hdl.handle.net/2123/29227.
Pełny tekst źródłaStreszczenie:
This study covered three aspects, namely; assessment of genetic diversity for rust
resistance genes among released cultivars, inheritance of adult plant resistance (APR) in two
North American wheat cultivars and genetic association between the stern rust resistance
gene Sr3 9 and the stripe rust resistance gene YrSp.
Queensland and northern New South Wales cultivars carried more diverse gene
combinations in comparison to rest of the nation. Genetic diversity for all three rust diseases
is a concern in Victoria and South Australia. There is need to release cultivars carrying
combinations of resistance genes against three rust diseases. This will ensure environmentally
safe control of rust diseases.
Cultivars Jagger carried three genes for APR to stripe rust. Combinations of these genes
provide high levels of resistance. Isolation of these genes individually was initiated and
molecular mapping will determine identities of these genes. American workers detected the
presence of Yr] 7 in at least one source of Jagger. Based on marker genotyping, the Jagger
source used in this study did not carry Yr] 7. Cultivar Katepwa carried a single APR gene for
stripe rust resistance. It is likely to be located on chromosome 2D.
Repulsion linkage between the Triticum speltoides-derived stem rust and leaf rust genes
Sr39/Lr35 and the stripe rust resistance gene YrSp was demonstrated. A recombination
faction of 7.7:tl.5 cM between these genes was computed. These results refuted the previous
location of YrSp in the short arm of chromosome 2B. Comparative results from other sources
suggested the location of YrSp in the long arm of chromosome 2B. Progenies from three
recombinant genotypes (Sr39Sr39YrSpyrSp) would enable the isolation of Sr39, Lr35 and
YrSp in a single genotype. Such triple rust resistant genotype will be useful in improving rust
resistance in future wheat cultivars.
41
Alruhaili, M. H. B. "Genetic diversity of African isolates of Toxoplasma gondii". Thesis, University of Salford, 2016. http://usir.salford.ac.uk/37753/.
Pełny tekst źródłaStreszczenie:
Toxoplasma gondii is an intracellular protozoan parasite and has the ability to infect all warm-blooded animals, including humans. While the three clonal lineages of T. gondii (I, II and III) predominate in North America and Europe, strains from other regions in the world appear to have more diverse genotypes. The aim of the current research is to analyse the level of genetic variation among local African T. gondii isolates in relation to their phenotype (genotype phenotype relationships). In this study, multi-locus nested PCR sequence analysis of seven Ugandan T. gondii isolates was applied using nine different genetic markers distributed across seven chromosomes and the apicoplast genome of T. gondii, which improved the discrimination power to detect variation among the local Ugandan strains. Although these markers were sufficient to separate global variation between T.gondii strains, they were not adequate to totally resolve within closely related local isolates. To understand the impact of local variation on strain diversity, whole genome sequence was generated for two Ugandan strains type II using Illumina MiSeq paired-end sequencing, revealing variations between these strains and the type II reference strain of T. gondii (TgME49). In this study, we have perhaps the first example of the deeper sequencing of isolates from the same geographical region at the same time point, which showed that they are non-identical. Novel polymorphisms were identified in a virulence associated gene in both Ugandan strains resulting in modification of the protein structure of this gene which could be associated with phenotype variation in the in vitro growth rate of these strains. Comparing the in vitro growth rates of the sympatric Ugandan strains, a cluster of 3 strains had higher growth. These were genotypically identical by using PCR sequencing technique, while the non-identical sympatric strains had lower growth rates, providing evidence that genotype may influence phenotype. An important finding was evidence of recombination between type II and III within three Ugandan strains, revealed through multi-locus PCR sequencing, and in an additional Ugandan strain through deeper whole genome sequencing. Six polymorphic markers were identified via analysis of three biologically relevant genes families (SRS, ROPs and GRA), enhancing the resolution power to identify variations among local type II strains of T. gondii. It is recommended that further study of these polymorphic markers is carried out and that they are added into the MLST analysis of T. gondii, especially between closely related local isolates.
42
Lazar, Katherine. "The genetic diversity of Teratosphaeria cryptica in Australia". Thesis, Lazar, Katherine (2016) The genetic diversity of Teratosphaeria cryptica in Australia. PhD thesis, Murdoch University, 2016. https://researchrepository.murdoch.edu.au/id/eprint/39531/.
Pełny tekst źródłaStreszczenie:
Teratosphaeria cryptica is one of the most important causal agents of Teratosphaeria leaf disease in plantations in Australia, the others being Teratosphaeria nubilosa and T. pseudonubilosa. While T. nubilosa has been distributed globally, T. cryptica and T. pseudonubilosa are only found in Australia and New Zealand. Teratosphaeria cryptica has a very broad distribution and host range within Australia. In this thesis the population genetics of T. cryptica was examined in order to determine its mode of reproduction, origin and patterns of movement within Australia, to look for evidence of cryptic speciation, and determine whether there is evidence for host preferences or spatial structure within and between populations.
Eleven primer sets were designed for polymorphic microsatellites regions for T. cryptica. These were then used on over 1000 samples of T. cryptica collected throughout its range within Australia; Western Australia (WA), Victoria (VIC), Tasmania (TAS), New South Wales (NSW) and into far north Queensland (QLD). Several aspects of the overall Australian population were revealed. The pathogen most likely originated in south eastern Australia (VIC, TAS and Southern NSW). In the eastern states there appears to be a division between the north (northern NSW and QLD) and the south (VIC, TAS and southern NSW) from which very different populations were found.
Within both the northern and southern areas of eastern Australia there was evidence of linkage disequilibrium in populations. Analysis with the program STRUCTURE found two clusters in the north and four clusters in the south. These clusters do not appear to represent cryptic species as there was evidence of admixture. Although QLD was not thoroughly sampled, the two northern clusters were not closely related and it is therefore proposed that they represent two separate migration events from the south. In vi the south, there was correlation (although also many exceptions) between clusters and host species (two clusters were associated mainly with E. globulus, another with E. nitens and another with E. obliqua). As out crossing requires physical proximity it is possible the clusters have arisen out of the host preference.
Teratosphaeria cryptica was foremost found to be homothallic. This, together with asexual reproduction often resulted in an immediate area (within 20m2) being dominated by one to three multilocus haplotypes (MLHs). In different areas however it was rare to find identical MLHs. There was one exception to this, MLH C274, which was found at multiple locations. It was almost exclusively found on E. globulus and had consistent culture morphology. It’s possible the widespread planting of E. globulus in south eastern Australia has changed the composition of the T. cryptica population with an increase in MLHs with a preference for E. globulus and suggest that this disease will continue to be a problem for plantations in south eastern Australia.
Teratosphaeria cryptica has been introduced into WA. There appears to have been at least two introductions. One of these probably occurred around the time it was first recorded in WA, the early 1990s. Although it may have been bought in with E. globulus for plantations, it could also have had different sources as many host species from south eastern Australia have been transported to WA. The evolutionary advantage of infecting endemic hosts appears to have led to a shift away from E. globulus and MLHs derived from this older introduction were rarely found in plantations. Most isolates collected from plantations were MLH C274, with the same host preference and culture morphology as found in VIC. The introduction of further MLHs, particularly those with a preference for E. globulus is of concern for plantations and quarantine procedures.
43
da, Fonseca Batista Vera Alexandra Garcia. "Defining marine meiofaunal genetic diversity using 454 sequencing". Thesis, Bangor University, 2011. https://research.bangor.ac.uk/portal/en/theses/defining-marine-meiofaunal-genetic-diversity-using-454-sequencing(549559f2-3dc7-4baf-b6e1-a5d1a17aef5a).html.
Pełny tekst źródła
44
Díaz, Oscar. "Genetic diversity in Elymus species (Triticeae) with emphasis on the Nordic region /". Svalöv : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1999. http://epsilon.slu.se/avh/1999/91-576-5493-X.pdf.
Pełny tekst źródła
45
Rasmussen, Greig S. "Memorializing the loss of genetic diversity, a genetic archive and memorial for Calgary". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0035/MQ66979.pdf.
Pełny tekst źródła
46
Masumbuko, Linus. "Study of genetic diversity and micropopagation of Coffea arabica L. and evaluation of genetic diversity in Cocos nucifera L. from Tanzania /". Alnarp : Dept. of Crop Science, Swedish University of Agricultural Sciences, 2005. http://epsilon.slu.se/200598.pdf.
Pełny tekst źródła
47
Selemani, George Paul. "Genetic diversity and population structure of plasmodium falciparum from four epidemiological locations in Malawi". Thesis, Nelson Mandela Metropolitan University, 2014. http://hdl.handle.net/10948/d1021026.
Pełny tekst źródłaStreszczenie:
In malaria-endemic regions, Plasmodium falciparum (P. falciparum) infection is characterized by extensive genetic/antigenic diversity. Describing this diversity provides important information about the local molecular epidemiology of infecting P. falciparum parasites. Intriguingly, one of the major obstacles to the development of an effective malaria vaccine has been the genetic polymorphisms exhibited by P. falciparum genes encoding targets of human immune system. This situation has necessitated the development of polyvalent vaccines with wide antigenic coverage that would increase the likelihood of vaccine efficacy that covers wide geographical areas of malaria endemic countries. Limited reports are available on the population genetic diversity and structure of P. falciparum in Malawi, and this is of particular concern as the country has put in place several interventions to combat the disease. The primary aim of the research project was to determine the genetic diversity and population structure of P. falciparum isolates and comparing complexity from four different epidemiological settings in Malawi using msp-2 gene polymorphisms. Samples were collected from four epidemiological locations in the north, centre and southern regions of Malawi. The diversity and genetic differentiation of P. falciparum populations were analyzed based on the highly polymorphic block 3 msp-2 gene. One hundred and twenty patient samples who presented with signs and symptoms of malaria and who had microscopically confirmed P. falciparum infection were enrolled in the study after they had satisfied the inclusion criteria. Parasite DNA was extracted from the blood spot on to filter paper and analyzed by genotyping the msp-2 gene using allele-specific nested PCR. A total of 28 msp-2 block 3 fragments, defined by the size and the allelic types were detected in the 102 patients. The length variants of the PCR product ranged from 240basepairs (bp) to 450bp for the K1/FC and 410bp to 780bp for the 3D7/IC allelic families. Isolates of the 3D7 alleles were predominant in the population (59 percent), compared to isolates of the K1/ FC27 alleles (41 percent) and for 3D7 and K1 most of the isolates were monoclonal infections. In comparisons between the sites, we observed the highest prevalence of mixed infection in Mwanza (46.7 percent) followed by Dwangwa (23.3 percent) compared to Bolero (16.7 percent) and Mitundu (16.7 percent). The difference in prevalence of mixed infections between Mwanza and the other sites was statistically significant (p=0.041). There was also a non-significant trend towards a higher mean genotype number per isolate in the children aged >5 years compared to those below 5 years of age. These data suggest differences in prevalence rates of mixed infections in different geographical/epidemiological settings in Malawi. Further studies are needed to confirm, with larger sample sizes, the observation of a non-significant trend towards higher multiclonality of infection in older children in malaria endemic areas of Malawi.
48
Atangana, Alain Rene. "Phenotypic diversity in fruit and seed traits, and neutral genetic diversity in Allanblackia Floribunda". Thesis, Université Laval, 2010. http://www.theses.ulaval.ca/2010/27171/27171.pdf.
Pełny tekst źródłaStreszczenie:
Allanblackia floribunda est un arbre des forêts denses humides tropicales valorisé pour la teneur élevée en acides gras de ses graines, essentiellement constitués d’acides stéarique et oléique dont l’efficacité dans la réduction du mauvais cholestérol de l’organisme humain a été prouvée. Pour cette raison, les graines de A. floribunda collectées en milieu naturel sont commercialisées. Toutefois, les travaux sur la culture de cette espèce sont encore à leur phase initiale. Nous avons déterminé la possibilité d’amélioration génétique de cette espèce en échantillonnant 17 à 40 fruits par arbre de 70 arbres distribués sur quatre sites en milieu naturel. La matière grasse a été extraite des graines, et les teneurs en acides stéarique et oléique estimées à l’aide de méthodes développées au cours de cette étude. La variation phénotypique des traits des fruits et des graines a été caractérisée dans et entre les arbres, et entre les sites. Les estimations de répétabilité des caractères mesurés ont été effectuées. Des corrélations phénotypiques entre les traits étudiés ont aussi été estimées, et quatre traits ont été retenus pour effectuer la sélection multi-caractère de 20 arbres-plus qui constitueront la population d’amélioration de cette espèce pour la production des graines. Nous avons par la suite isolé 10 marqueurs moléculaires de type microsatellite polymorphes à partir de A. floribunda, et sept de ces marqueurs étaient polymorphes à la fois chez Allanblackia gabonensis et Allanblackia stanerana. La variation de huit loci microsatellites a permis de caractériser la structure génétique neutre de 10 populations de A. floribunda de zone de forêt naturelle du Cameroun, puis d’inférer l’histoire récente des forêts humides d’Afrique Centrale. Aucune différence significative n’a été observée entre les paramètres génétiques de la population d’amélioration et celle existant en milieu naturel indiquant qu’une amélioration de cette espèce à partir des 20 arbres sélectionnés ne réduirait pas sa diversité génétique neutre. Toutefois, une légère augmentation du taux de consanguinité a été observée dans la population d’amélioration, et des recommandations sont formulées pour la conservation des ressources génétiques durant l’amélioration de A. floribunda.Allanblackia floribunda or tallow tree is a tropical forest-tree species that is valued for its seeds, which are rich in hard fat consisting mostly of stearic and oleic acids, reported to lower plasma cholesterol levels, thus reducing the risks of heart attack. Owing to this fat profile, Allanblackia oil is used for margarine production and in soap and ointments manufacture, and seeds extracted from Allanblackia fruits by local communities are traded. We determined whether the species could be genetically improved for fruit/seed production by sampling 17 to 40 fruits from each of 70 trees that were distributed among four sites in wild stands. Fat was extracted from the seeds, and stearic and oleic acid content of the fat was estimated using methods developed in this study. Phenotypic variation in fruit/seed traits was assessed within- and among-trees, and among sites. Repeatabilities were estimated for measured characters, and relationships between these characters investigated. Twenty “plus trees” were selected for breeding, and implications for improvement discussed. Then we isolated and characterized ten microsatellite primer pairs for A. floribunda. Seven of these microsatellite loci were polymorph for both Allanblackia gabonensis and Allanblackia stanerana species as well. Using eight informative microsatellite loci, we have characterized the genetic structure of A. floribunda natural populations from Cameroon, and inferred the recent history of rainforests from Central Africa. No significant difference was identified in genetic parameters between wild stands and the breeding population, indicating that breeding A. floribunda from 20 trees would not reduce nuclear genetic diversity. However, a slight increase in inbreeding was observed in the breeding population, and recommendations for genetic diversity conservation during tree improvement in the species are made.
49
Acar, Hande. "Bioinformatic Analyses In Microsatellite-based Genetic Diversity Of Turkish Sheep Breeds". Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612585/index.pdf.
Pełny tekst źródłaStreszczenie:
In the present study, within and among breed genetic diversity in thirteen Turkish sheep breeds (Sakiz, Karagül, Hemsin, Ç
ine Ç
apari, Norduz, Herik, Akkaraman, Dagliç
, Gö
kç
eada, Ivesi, Karayaka, Kivircik and Morkaraman
in total represented by 628 individuals) were analyzed based on 20 microsatellite loci. Loci were amplified by Polymerase Chain Reactions and products were electronically recorded and converted into [628 x 20] matrix representing genotypes of individuals. Reliability of the genotyping and genetic diversity analyses were done by means of various bioinformatics tools. For the analyses, various statistical methods (Fisher'
s Exact Test, Neighbor-Joining tree construction, Factorial Correspondence Analysis (FCA), Analysis of Molecular Variation, Structure Analysis and Delaunay Analysis) were used. Since, inputs of some software were not compatible with the outputs of other software some Java classes were written whenever necessary. Analyses revealed that among the major breeds Dagliç
, Karayaka and Morkaraman breeds are highly admixed but Kivircik, Akkaraman and Ivesi are relatively distinct. Among the minor breeds, distinctness of Hemsin, Sakiz, Ç
ine Ç
apari, Gö
kç
eada and Karagü
l are more pronounced compared to all of the examined breeds. Since highly admixed individuals can be identified by Structure and FCA tests, results of the present study, which is part of a national project with the acronym TURKHAYGEN-I (www.turkhaygen.gov.tr), were found to be promising in establishing and managing relatively pure conservation flocks for the Turkish native sheep breeds which are believed to be the reservoirs of genetic variability.
50
Chipili, Jack. "Characterisation of populations of Magnaporthe grisea the rice blast fungus in some of the West African countries". Thesis, University of Exeter, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326952.
Pełny tekst źródła