Dissertations / Theses on the topic 'Population genetics Mathematics'
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Herbots, Hilde Maria Jozefa Dominiek. "Stochastic models in population genetics : genealogy and genetic differentiation in structured populations." Thesis, Queen Mary, University of London, 1994. http://qmro.qmul.ac.uk/xmlui/handle/123456789/1482.
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The theory of probability and stochastic processes is applied to a current issue in population genetics, namely that of genealogy and genetic differentiation in subdivided populations. It is proved that under a reasonable model for reproduction and migration, the ancestral process of a sample from a subdivided population converges weakly, as the subpopulation sizes tend to infinity, to a continuous-time Markov chain called the "structured coalescent". The moment-generating function, the mean and the cond moment of the time since the most recent common ancestor (called the "coalescence time") of a pair of genes are calculated explicitly for a range of models of population structure. The value of Wright's coefficient FST, which serves as a measure of the subpopulation differentiation and which can be related to the coalescence times of pairs of genes sampled within or among subpopulations, is calculated explicitly for various models of population structure. It is shown that the dependence of FST on the mutation rate may be more marked than is generally believed, particularly when gene flow is restricted to an essentially one-dimensional habitat with a large number of subpopulations. Several more general results about genealogy and subpopulation differentiation are proved. Simple relationships are found between moments of within and between population coalescence times. Weighting each subpopulation by its relative size, the asymptotic behaviour of FST at large mutation rates is independent of the details of population structure. Two sets of symmetry conditions on the population structure are found for which the mean coalescence time of a pair of genes from a single subpopulation is independent of the migration rate and equal to that of two individuals from a panmictic population of the same total size. Under graph-theoretic conditions on the population structure, there is a uniform relationship between the FST value of a pair of neighbouring subpopulations, in the limit of zero mutation rate, and the migration rate
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Levin, Alex Ph D. (Alexander) Massachusetts Institute of Technology. "Graphs, matrices, and populations : linear algebraic techniques in theoretical computer science and population genetics." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/83695.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Department of Mathematics, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 149-155).
In this thesis, we present several algorithmic results for problems in spectral graph theory and computational biology. The first part concerns the problem of spectral sparsification. It is known that every dense graph can be approximated in a strong sense by a sparse subgraph, known as a spectral sparsifier of the graph. Furthermore, researchers have recently developed efficient algorithms for computing such approximations. We show how to make these algorithms faster, and also give a substantial improvement in space efficiency. Since sparsification is an important first step in speeding up approximation algorithms for many graph problems, our results have numerous applications. In the second part of the thesis, we consider the problem of inferring human population history from genetic data. We give an efficient and principled algorithm for using single nucleotide polymorphism (SNP) data to infer admixture history of various populations, and apply it to show that Europeans have evidence of mixture with ancient Siberians. Finally, we turn to the problem of RNA secondary structure design. In this problem, we want to find RNA sequences that fold to a given secondary structure. We propose a novel global sampling approach, based on the recently developed RNAmutants algorithm, and show that it has numerous desirable properties when compared to existing solutions. Our method can prove useful for developing the next generation of RNA design algorithms.
by Alex Levin.
Ph.D.
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Ishida, Yoichi. "Secret analogies mathematics, ecology, and evolution /." abstract and full text PDF (free order & download UNR users only), 2007. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1442878.
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Reich, David Emile. "Genetic analysis of human evolutionary history with implications for gene mapping." Thesis, University of Oxford, 1999. http://ora.ox.ac.uk/objects/uuid:9e3a3eb7-3cce-4494-82e8-8616fabed145.
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Genetic variation contains detailed and quantitative evidence about the history of populations. The historical traces of demographic growth and contraction, as well as the history of human disease, have left traces on the patterns of modern variation and can be studied by sampling present-day populations. However, the data sets that are necessary in order to take full advantage of this living archaeological record have not been available until recently. The quality and quantity of data have increased dramatically during the past decade because of the identification of polymorphisms, including SNPs and microsatellites, that are much more amenable to mathematical modeling and efficient genotyping than earlier marker systems. The research in this thesis has been carried out in response to the need to provide new methods of analysis to match the new types of data. Chapter 1 describes multilocus tests of demographic history and their application to real data. Chapter 2 describes how the pattern of linkage disequilibrium around a disease-predisposing mutation can be used to estimate the date of a mutation that is, the age of the most recent common ancestor of a set of modern samples. Finally, Chapter 3 draws several direct connections between human evolutionary history and medical genetics.
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Gjini, Erida. "Bridging between parasite genomic data and population processes : trypanosome dynamics and the antigenic archive." Thesis, University of Glasgow, 2012. http://theses.gla.ac.uk/3375/.
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Antigenic variation processes play a central role in parasite invasion and chronic infectious disease, and are likely to respond to host immune mechanisms and epidemiological characteristics. Whether changes in antigenic variation strategies lead to net positive or negative effects for parasite fitness is unclear. To improve our understanding of pathogen evolution, it is important to investigate the mechanisms by which pathogens regulate antigenic variant expression. This involves consideration of the complex interactions that occur between parasites and their hosts, and top-down and bottom-up factors that might drive changes in the genetic architecture of their antigenic archives. Increasing availability of pathogen genomic data offers new opportunities to understand the fundamental mechanisms of immune evasion and pathogen population dynamics during chronic infection. Motivated by the growing knowledge on the antigenic variation system of the sleeping sickness parasite, the African trypanosome, in this thesis, we present different models that analyze antigenic variation of this parasite at different biological scales, ranging from the within-host level, to between-host transmission, and finally the parasite genetics level. First, we describe mechanistically how the structure of the antigenic archive impacts the parasite population dynamics within a single host, and how it interplays with other within-host processes, such as parasite density-dependent differentiation into transmission life-stages and specific host immune responses. Our analysis focuses first on a single parasitaemia peak and then on the dynamics of multiple peaks that rely on stochastic switching between groups of parasite variants. We show that the interplay between the two types of parasite control within the host: specific and general, depends on the modular structure of the parasite antigenic archive. Our modelling reveals that the degree of synchronization in stochastic variant emergence (antigenic block size) determines the relative dominance of general over specific control within a single peak, and can divide infection scenarios into stationary and oscillatory regimes. A requirement for multiple-peak dynamics is a critical switch rate between blocks of antigenic variants, which depends on host characteristics, such as the immune delay, and implies constraints on variant surface glycoprotein (VSG) archive genetic diversification. Secondly, we study the interactions between the structure and function of the antigenic archive at the transmission level. By using nested modelling, we show that the genetic architecture of the archive has important consequences for pathogen fitness within and between hosts. We find host-dependent optimality criteria for the antigenic archive that arise as a result of typical trade-offs between parasite transmission and virulence. Our analysis suggests that different traits of the host population can select for different aspects of the antigenic archive, reinforcing the importance of host heterogeneity in the evolutionary dynamics of parasites. Variant-specific host immune competence is likely to select for larger antigenic block sizes. Parasite tolerance and host life-span are likely to select for whole archive expansion as more archive blocks provide the parasite with a fitness advantage. Within-host carrying capacity, resulting from density-dependent parasite regulation, is likely to impact the evolution of between-block switch rates in the antigenic archive. Our study illustrates the importance of quantifying the links between parasite genetics and within-host dynamics, and suggests that host body size might play a significant role in the evolution of trypanosomes. In Chapters 4 and 5 we consider the genetics behind trypanosome antigenic variation. Antigen switch rates are thought to depend on a range of genetic features, among which, the genetic identity between the switch-off and switch-on gene. The subfamily structure of the VSG archive is important in providing the conditions for this type of switching to occur. We develop a hidden Markov model to describe and estimate evolutionary processes generating clustered patterns of genetic identity between closely related gene sequences. Analysis of alignment data from high-identity VSG genes in the silent antigen gene archive of the African trypanosome identifies two scales of subfamily diversification: local clustering of sequence mismatches, a putative indicator of gene conversion events with other lower-identity donor genes in the archive, and the sparse scale of isolated mismatches, likely to arise from independent point mutations. In addition to quantifying the respective rates of these two processes, our method yields estimates for the gene conversion tract length distribution and the average diversity contributed locally by conversion events. Model fitting is conducted for a range of models using a Bayesian framework. We find that gene conversion events with lower-identity partners are at least 5 times less common than point mutations for VSG pairs, and the average imported conversion tract is short. However, due to the high frequency of mismatches in converted segments, the two processes have almost equal impact on the rate of sequence diversification between VSG sub-family members. We are able to disentangle the most likely locations of point mutations vs. conversions on each aligned gene pair. Finally we model VSG archive diversification at the global scale, as a result of opposing evolutionary forces: point mutation, which induces diversification, and gene conversion, which promotes global homogenization. By adopting stochastic simulation and theoretical approaches such as population genetics and the diffusion approximation, we find how the stationary identity configuration of the archive depends on mutation and conversion parameters. By fitting the theoretical form of the distribution to the current VSG archive configuration, we estimate the global rates of gene conversion and point mutation. The relative dominance of mutation as an evolutionary force quantifies the high divergence propensity of VSG genes in response to host immune pressures. The success of our models in describing realistic infection patterns and making predictions about the fitness consequences of the parasite antigenic archive illustrates the advantage of using integrative approaches that bridge between different biological scales. Even though quantifying the genetic signatures of antigenic variation remains a challenging task, cross-disciplinary analyses and mechanistic modelling of parasite genomic data can help in this direction, to better understand parasite evolution.
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Lundy, Ian J. "Theoretical population genetics of spatially structured populations /." Title page, contents and summary only, 1997. http://web4.library.adelaide.edu.au/theses/09PH/09phl962.pdf.
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Loucoubar, Cheikh. "Statistical genetic analysis of infectious disease (malaria) phenotypes from a longitudinal study in a population with significant familial relationships." Phd thesis, Université René Descartes - Paris V, 2012. http://tel.archives-ouvertes.fr/tel-00685104.
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Long term longitudinal surveys have the advantage to enable several sampling of the studied phenomena and then, with the repeated measures obtained, find a confirmed tendency. However, these long term surveys generate large epidemiological datasets including more sources of noise than normal datasets (e.g. one single measure per observation unit) and potential correlation in the measured values. Here, we studied data from a long-term epidemiological and genetic survey of malaria disease in two family-based cohorts in Senegal, followed for 19 years (1990-2008) in Dielmo and for 16 years (1993-2008) in Ndiop. The main objectives of this work were to take into account familial relationships, repeated measures as well as effect of covariates to measure both environmental and host genetic (heritability) impacts on the outcome of infection with the malaria parasite Plasmodium falciparum, and then use findings from such analyses for linkage and association studies. The outcome of interest was the occurrence of a P. falciparum malaria attack during each trimester (PFA). The two villages were studied independently; epidemiological analyses, estimation of heritability and individual effects were then performed in each village separately. Linkage and association analyses used family-based methods (based on the original Transmission Disequilibrium Test) known to be immune from population stratification problems. Then to increase sample size for linkage and association analyses, data from the two villages were used together.
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Olsson, Fredrik. "Inbreeding, Effective Population Sizes and Genetic Differentiation : A Mathematical Analysis of Structured Populations." Doctoral thesis, Stockholms universitet, Matematiska institutionen, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-115708.
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This thesis consists of four papers on various aspects of inbreeding, effective population sizes and genetic differentiation in structured populations, that is, populations that consist of a number of subpopulations. Three of the papers concern age structured populations, where in the first paper we concentrate on calculating the variance effective population size (NeV) and how NeV depends on the time between measurements and the weighting scheme of age classes. In the third paper we develop an estimation procedure of NeV which uses age specific demographic parameters to obtain approximately unbiased estimates. A simulation method for age structured populations is presented in the fourth paper. It is applicable to models with multiallelic loci in linkage equilibrium. In the second paper, we develop a framework for analysis of effective population sizes and genetic differentiation in geographically subdivided populations with a general migration scheme. Predictions of gene identities and gene diversities of the population are presented, which are used to find expressions for effective population sizes (Ne) and the coefficient of gene differentiation (GST). We argue that not only the asymptotic values of Ne and GST are important, but also their temporal dynamic patterns. The models presented in this thesis are important for understanding how different age decomposition, migration and reproduction scenarios of a structured population affect quantities, such as various types of effective sizes and genetic differentiation between subpopulations.At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 4: Submitted.
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Xu, Yiyang. "Topics in population genetics and mathematical evolutionary biology." Thesis, University of Bristol, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.682366.
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Part A studies the optimal strategies of seed germination problems where the population has a class structure under a fluctuating environment . In particular, a multidimensional age-class model is studied using a dynamical programming method. Numerical results about the so-called optimal stochastic strategy which consists of information about previous environmental states are computed. Comparing the optimal stochastic strategy with the optimal population-based strategy shows that the optimal stochastic strategy is highly effective in genera.l. A potentially useful diffusion approximation for the seed germination problem is also derived with numerical results. For part B, a multi-dimensional Moran model is studied using a diffusion approximation approach. The scaling limit and corresponding governing stochastic partial differential equations (SDEs) are derived. An expansion method is used to approximate the stationary distribution of the SDEs. An approximation formula for the effective migration rate is then derived.
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Martin, Anna. "Mathematical modeling of seed bank dynamics in population genetics." Thesis, Uppsala universitet, Institutionen för informationsteknologi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-321191.
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We study the genealogical structure of samples from a population for which any givengeneration is made up of direct descendants from one randomly chosen previousgeneration. These occur in nature when there are seed banks or egg banks allowingan individual to leave offspring several generations in the future. Kaj et al. studied in2001 the case where any given generation is made up of descendants from severalprevious generations and showed how this temporal structure in the reproductionmechanism causes a decrease in the coalescence rate. In this project we will showthat having all samples pick their parents in one randomly chosen generation will leadto a coalescent process which is equivalent to a time shifted version of Kingman’scoalescent, time shifted with the age distribution of the seed bank.
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Auton, Adam. "The estimation of recombination rates from population genetic data." Thesis, University of Oxford, 2007. http://ora.ox.ac.uk/objects/uuid:dc38045b-725d-4afc-8c76-94769db3534d.
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Genetic recombination is an important process that generates new combinations of genes on which natural selection can operate. As such, an understanding of recombination in the human genome will provide insight into the evolutionary processes that have shaped our genetic history. The aim of this thesis is to use samples of population genetic data to explore the patterns of variation in the rate of recombination in the human genome. To do this I introduce a novel means of estimating recombination rates from population genetic data. The new, computationally efficient method incorporates a model of recombination hotspots that was absent in existing methods. I use samples from the International HapMap Project to obtain recombination rate estimates for the autosomal portion of the genome. Using these estimates, I demonstrate that recombination has a number of interesting relationships with other genome features such as genes, DNA repeats, and sequence motifs. Furthermore, I show that genes of differing function have significantly different rates of recombination. I explore the relationship between recombination and specific sequence motifs and argue that while sequence motifs are an important factor in determining the location of recombination hotspots, the factor that controls motif activity is unknown. The observation of many relationships between recombination and other genome features motivates an attempt to quantify the contributions to the recombination rate from specific features. I employ a wavelet analysis to investigate scale-specific patterns of recombination. In doing so, I reveal a number of highly significant correlations between recombination and other features of the genome at both the fine and broad scales, but find that relatively little of the variation in recombination rates can be explained. I conclude with a discussion of the results contained in the body of the thesis, and suggest a number of areas for future research.
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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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Jiang, Hongyu. "Population genetics genealogies under selection." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:141f4e19-d13a-409e-a7c7-aeaabd6b9b88.
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In the presence of selection and mutation, the genealogy of a given sample configuration can be described by two classes of ancestral processes, namely the coalescent-in-a-random-background model of Kaplan et al. (1988) and the dual process with typed lines of Etheridge and Griffiths (2009). These two processes are based on the same forwards population genetics model. However, in the former model, selection is reflected in the ancestral frequencies in the population, while in the latter model, there are branching events that generate virtual ancestral lines. We simulate the dual processes with typed lines and derive the limits of the two ancestral processes under strong selection and under selection-mutation balance to address the question of to what extent the genealogy is distorted. The two ancestral processes generate the same limiting genealogy. In a two-allele population under strong selection, the disfavoured individuals in the sample are instantaneously converted to a random number of favoured individuals, and the limiting genealogy is governed by the usual Kingman’s coalescent. Under selection-mutation balance, all disfavoured individuals in the sample are instantaneously converted to the favoured type, and the limiting genealogy is determined by a time-changed Kingman’s coalescent. The proofs of these limiting processes are based on the convergence result of Mohle (1998, Lemma 1). The studies of selection-mutation balance are then extended to an additive selection model, where each individual is composed of L diallelic loci. In the corresponding dual process with typed lines, the evolution of the virtual lines on a faster timescale can be approximated by a deterministic process, while the evolution of the real lines is independent of the virtual lines. The structure in the limiting genealogy collapses to Kingman’s coalescent. We also let L tend to infinity, and obtain a full description of the limiting genealogy in the background selection model.
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Tran, Tat Dat. "Information Geometry and the Wright-Fisher model of Mathematical Population Genetics." Doctoral thesis, Universitätsbibliothek Leipzig, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-90508.
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My thesis addresses a systematic approach to stochastic models in population genetics; in particular, the Wright-Fisher models affected only by the random genetic drift. I used various mathematical methods such as Probability, PDE, and Geometry to answer an important question: \"How do genetic change factors (random genetic drift, selection, mutation, migration, random environment, etc.) affect the behavior of gene frequencies or genotype frequencies in generations?”.
In a Hardy-Weinberg model, the Mendelian population model of a very large number of individuals without genetic change factors, the answer is simple by the Hardy-Weinberg principle: gene frequencies remain unchanged from generation to generation, and genotype frequencies from the second generation onward remain also unchanged from generation to generation.
With directional genetic change factors (selection, mutation, migration), we will have a deterministic dynamics of gene frequencies, which has been studied rather in detail. With non-directional genetic change factors (random genetic drift, random environment), we will have a stochastic dynamics of gene frequencies, which has been studied with much more interests. A combination of these factors has also been considered.
We consider a monoecious diploid population of fixed size N with n + 1 possible alleles at a given locus A, and assume that the evolution of population was only affected by the random genetic drift. The question is that what the behavior of the distribution of relative frequencies of alleles in time and its stochastic quantities are.
When N is large enough, we can approximate this discrete Markov chain to a continuous Markov with the same characteristics. In 1931, Kolmogorov first introduced a nice relation between a continuous Markov process and diffusion equations. These equations called the (backward/forward) Kolmogorov equations which have been first applied in population genetics in 1945 by Wright.
Note that these equations are singular parabolic equations (diffusion coefficients vanish on boundary). To solve them, we use generalized hypergeometric functions. To know more about what will happen after the first exit time, or more general, the behavior of whole process, in joint work with J. Hofrichter, we define the global solution by moment conditions; calculate the component solutions by boundary flux method and combinatorics method.
One interesting property is that some statistical quantities of interest are solutions of a singular elliptic second order linear equation with discontinuous (or incomplete) boundary values. A lot of papers, textbooks have used this property to find those quantities. However, the uniqueness of these problems has not been proved. Littler, in his PhD thesis in 1975, took up the uniqueness problem but his proof, in my view, is not rigorous. In joint work with J. Hofrichter, we showed two different ways to prove the uniqueness rigorously. The first way is the approximation method. The second way is the blow-up method which is conducted by J. Hofrichter.
By applying the Information Geometry, which was first introduced by Amari in 1985, we see that the local state space is an Einstein space, and also a dually flat manifold with the Fisher metric; the differential operator of the Kolmogorov equation is the affine Laplacian which can be represented in various coordinates and on various spaces. Dynamics on the whole state space explains some biological phenomena.
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KOT, MARK. "THE EFFECTS OF PARAMETRIC EXCITATION AND OF DISPERSAL ON THE DYNAMICS OF DISCRETE-TIME POPULATION MODELS." Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184074.
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Parametric excitation and dispersal are added to discrete-time population models. Discrete-time models for growth with dispersal share many of the attributes of reaction-diffusion equations. At the same time, these models readily exhibit period doubling and chaos. Large parametric excitation (seasonality) is inevitably destabilizing, but mild seasonality may have a pronounced stabilizing effect. Seasonality also allows for the coexistence of alternative stable states (equilibria, cycles, chaos). Many examples are presented.
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López, de Rioja Víctor. "Population range expansions, with mathematical applications to interacting systems and ancient human genetics." Doctoral thesis, Universitat de Girona, 2019. http://hdl.handle.net/10803/667171.
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The thesis studies from an analytical and computational perspective, and by using reaction-diffusion equations, the spatiotemporal evolution of different populations.
First, the dynamics of the T7 bacteriophage infecting the E. coli bacteria is studied. By adding the delayed time in diffusion and reaction terms, as well as new mathematical terms biologically sound, we can achieve results that accurately match the experimental propagation speeds.
Secondly, different mathematical models are proposed to correctly understand the expansion of VSV in Glioblastoma. The only model capable of this explanation is the system which understands the delay time for the processes of diffusion and reaction.
Finally, the Neolithic transition through Europe is explained by studying ancient genetic DNA samples alongside mathematical simulations. Focusing on haplogroup K, the model is built by analyzing the two Neolithic diffusion mechanisms: demic and cultural. The simulations show that the transition is basically demic, with only 2% of the Neolithic farmers interacting culturallyAquesta tesi estudia des d’un punt de analític i computacional, gràcies a les equacions de reacció-difusió, l’evolució espaciotemporal de diferents poblacions que interactuen entre elles. El primer article estudia la dinàmica del bacteriòfag T7 infectant el bacteri E. coli. Gràcies a la incorporació del temps de retard en els termes de difusió i reacció, així com de nous termes matemàtics amb sentit biològic, aconseguim uns resultats que s’ajusten millor a les velocitats de propagació. El segon article aplica diferents models matemàtics per entendre millor l’expansió del VSV en Glioblastomes. L'únic model capaç d'explicar de manera correcte el sistema té en compte el temps de retard per als processos de difusió i reacció. L’últim article explica la transició del Neolític a través d’Europa utilitzant mostres genètiques antigues i simulacions matemàtiques. Centrant-nos en l’haplogrup K, el model es construeix tenint en compte els dos mecanismes de difusió neolítica: dèmica i cultural. Les simulacions mostren que la transició és bàsicament dèmica, on només el 2% dels neolítics interaccionen culturalment
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Lipson, Mark (Mark Israel). "New statistical genetic methods for elucidating the history and evolution of human populations." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/89873.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mathematics, 2014.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 165-173).
In the last few decades, the study of human history has been fundamentally changed by our ability to detect the signatures left within our genomes by adaptations, migrations, population size changes, and other processes. Rapid advances in DNA sequencing technology have now made it possible to interrogate these signals at unprecedented levels of detail, but extracting more complex information about the past from patterns of genetic variation requires new and more sophisticated models. This thesis presents a suite of sensitive and efficient statistical tools for learning about human history and evolution from large-scale genetic data. We focus first on the problem of admixture inference and describe two new methods for determining the dates, sources, and proportions of ancestral mixtures between diverged populations. These methods have already been applied to a number of important historical questions, in particular that of tracing the course of the Austronesian expansion in Southeast Asia. We also report a new approach for estimating the human mutation rate, a fundamental parameter in evolutionary genetics, and provide evidence that it is higher than has been proposed in recent pedigree-based studies.
by Mark Lipson.
Ph. D.
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Arpin, Sheree. "Using Mathematical Models to Investigate Phenotypic Oscillations in Cichlid Fish: A Case of Frequency-dependent Selection." Diss., The University of Arizona, 2007. http://hdl.handle.net/10150/195981.
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Perissodus microlepis is a species of cichlid fish endemic to Lake Tanganyika (Africa). Adult P. microlepis are lepidophages, feeding on the scales of other living fish. As an adaptation for this feeding behavior P. microlepis exhibit lateral asymmetry with respect to jaw morphology: the mouth either opens to the right or left side of the body. Field data illustrate a temporal phenotypic oscillation in the mouth-handedness, and this oscillation is maintained by frequency-dependent selection. To better understand the oscillation, Takahashi and Hori model frequency-dependent selection in P. microlepis using a population genetic model. Their results are intriguing, and the purpose of this dissertation is to improve and extend their model, which fails to account for important biological aspects.We model P. microlepis with a novel approach that fuses the disparate modeling traditions of population genetics and population dynamics; we account for both processes since, in the case of P. microlepis, they occur on the same time scale (a case of microevolution). We construct our models using systems of difference equations. We prove the existence and uniqueness of a positive equilibrium, which corresponds to a 1 : 1 phenotypic ratio. Using a local stability and bifurcation analysis, we show that the equilibrium becomes unstable when frequency-dependent selection is sufficiently strong. We determine necessary and sufficient conditions for onset of oscillation. Local bifurcation analysis indicates key features of the oscillation that may suggest critical experiments.We determine the role of stage structure and the role of strong and weak intraspecific competition. We show that stage-structure is not necessary for, but enhances, oscillatory behavior. Finally we demonstrate the complicated interplay between population dynamic and population genetic processes. Our findings indicate that classical population genetic models can fail to elucidate complex dynamics.
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Pieper, Daniel [Verfasser], and Martin [Akademischer Betreuer] Hutzenthaler. "Many-demes limit for interacting diffusions with applications in population genetics / Daniel Pieper ; Betreuer: Martin Hutzenthaler." Duisburg, 2020. http://d-nb.info/1213245508/34.
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Hustedt, Thiemo [Verfasser]. "The Moran model of population genetics : case studies with recombination and selection / Thiemo Hustedt. Fakultät für Mathematik." Bielefeld : Universitätsbibliothek Bielefeld, Hochschulschriften, 2012. http://d-nb.info/1024640523/34.
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Forest, Marie. "Simultaneous estimation of population size changes and splits times using importance sampling." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:8c067a3d-44d5-468a-beb5-34c5830998c4.
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The genome is a treasure trove of information about the history of an individual, his population, and his species. For as long as genomic data have been available, methods have been developed to retrieve this information and learn about population history. Over the last decade, large international genomic projects (e.g. the HapMap Project and the 1000 Genomes Project) have offered access to high quality data collected from thousands of individuals from a vast number of populations. Freely available to all, these databases offer the possibility to develop new methods to uncover the history of the peopling of the world by modern humans. Due to the complexity of the problem and the large amount of available data, all developed methods either simplify the model with strong assumptions or use an approximation; they also dramatically down-sample their data by either using fewer individuals or only portions of the genome. In this thesis, we present a novel method to jointly estimate the time of divergence of a pair of populations and their variable sizes, a previously unsolved problem. The method uses multiple regions of the genome with low recombination rate. For each region, we use an importance sampler to build a large number of possible genealogies, and from those we estimate the likelihood function of parameters of interest. By modelling the population sizes as piecewise constant within fixed time intervals, we aim to capture population size variation through time. We show via simulation studies that the method performs well in many situations, even when the model assumptions are not totally met. We apply the method to five populations from the 1000 Genomes Project, obtaining estimates of split times between European groups and among Europe, Africa and Asia. We also infer shared and non-shared bottlenecks in out-of- Africa groups, expansions following population separations, and the sizes of ancestral populations further back in time.
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Gayley, Todd Warwick. "Genetic models of two-phenotype frequency-dependent selection." Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184883.
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The aim of this study is to place a wide variety of two-phenotype frequency-dependent selection models into a unified population-genetic framework. This work is used to illuminate the possible genetic constraints that may exist in such models, and to address the question of evolutionary modification of these constraints. The first part of Chapter 1 synthesizes from the literature a general framework for applying a genetic structure to a simple class of two-phenotype models. It shows that genetic constraints may prevent the population from achieving a predicted phenotypic equilibrium, but the population will equilibrate at a point that is as close as possible to the phenotypic equilibrium. The second part of Chapter 1 goes on to ask whether evolutionary modification of the genetic system might be expected to remove these constraints. Chapter 2 provides an example of the application of the framework developed in Chapter 1. It presents re-analysis of a model for the evolution of social behavior by reciprocation (Brown et al. 1982). The genetic results of Chapter 1 apply to this model without modification. I show that Brown et al. were unnecessarily restrictive in their assumptions about the types of genetic systems that support their conclusions. Chapter 3 discusses some models for the evolution of altruism that do not fit the assumptions of Chapter 1, despite their two-phenotype structure. These models violate the fundamental assumption of Chapter 1, this being the way in which individual fitness is derived from the behavioral fitnesses. The first part is a complete, in-depth analysis of diploid sib-sib kin selection. I show that some results from the basic model can be used, provided the behavioral inclusive fitness functions are substituted for the true behavioral fitnesses. The second part is an analysis of the validity of the concept of behavioral structure, as introduced by Michod and Sanderson (1985). I show that this concept is flawed as a general principle. Chapter 4 extends the basic model to the case of sex-allocation evolution. I show how many of the central results of sex-allocation theory can be derived more simply using a two-phenotype framework.
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Wittmann, Meike [Verfasser], and Dirk [Akademischer Betreuer] Metzler. "Stochastic models for the ecology and population genetics of introduced species / Meike Wittmann. Betreuer: Dirk Metzler." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2014. http://d-nb.info/1047062380/34.
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Straulino, Daniel. "Selection in a spatially structured population." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:3a20f7a3-27cd-4cbb-9e88-7ebb21ce4e0d.
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This thesis focus on the effect that selection has on the ancestry of a spatially structured population. In the absence of selection, the ancestry of a sample from the population behaves as a system of random walks that coalesce upon meeting. Backwards in time, each ancestral lineage jumps, at the time of its birth, to the location of its parent, and whenever two ancestral lineages have the same parent they jump to the same location and coalesce. Introducing selective forces to the evolution of a population translates into branching when we follow ancestral lineages, a by-product of biased sampling forwards in time. We study populations that evolve according to the Spatial Lambda-Fleming-Viot process with selection. In order to assess whether the picture under selection differs from the neutral case we must consider the timescale dictated by the neutral mutation rate Theta. Thus we look at the rescaled dual process with n=1/Theta. Our goal is to find a non-trivial rescaling limit for the system of branching and coalescing random walks that describe the ancestral process of a population. We show that the strength of selection (relative to the mutation rate) required to do so depends on the dimension; in one and two dimensions selection needs to be stronger in order to leave a detectable trace in the population. The main results in this thesis can be summarised as follows. In dimensions three and higher we take the selection coefficient to be proportional to 1/n, in dimension two we take it to be proportional to log(n)/n and finally, in dimension one we take the selection coefficient to be proportional to 1/sqrt(n). We then proceed to prove that in two and higher dimensions the ancestral process of a sample of the population converges to branching Brownian motion. In one dimension, provided we do not allow ancestral lineages to jump over each other, the ancestral process converges to a subset of the Brownian net. We also provide numerical results that show that the non-crossing restriction in one dimension cannot be lifted without a qualitative change in the behaviour of the process. Finally, through simulations, we study the rate of convergence in the two-dimensional case.
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Xifara, Dionysia-Kiara. "The detection, structure and uses of extended haplotype identity in population genetic data." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:9fabc91a-dd07-4deb-b722-f6b9110b34fb.
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In large-scale population genomic data sets, individual chromosomes are likely to share extended regions of haplotype identity with others in the sample. Patterns of local haplotype sharing can be highly informative about many processes including historical demography, selection and recombination. However, in outbred diploid populations, the identification of extended shared haplotypes is not straightforward, particularly in the presence of low levels of genotyping error. Here, we introduce a model-based method for accurately detecting extended haplotype sharing between sets of individuals from unphased data. We describe two implementations of the algorithm that can be applied to data sets consisting of thousands of samples. The method leads naturally to an approach for statistical haplotype estimation, which is shown to be comparable in accuracy to current methods. By applying the method to genome-wide SNP data from over 5,000 samples from the UK we show that the N50 maximal haplotype sharing between unrelated samples is typically 2cM, consistent with a population history of rapid exponential growth that started approx. 125 generations ago. In contrast, within two Greek population isolates of approx. 700 individuals the N50 for maximal haplotype sharing is 12.5cM, while for an unrelated Greek sample of the same size the N50 is 1.3cM. By assessing the size and geographical distribution of maximal haplotype sharing within and between all Greek cohorts, we make inference on the extent of isolatedness of each cohort and on recent migration. We additionally date recent coancestry to about 10 generations for the isolates and 90 generations for the unrelated sample, and finnally attempt to date the time of divergence between them.
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González, Casanova Soberón Adrián [Verfasser], Jochen [Akademischer Betreuer] Blath, Noemi [Akademischer Betreuer] Kurt, Jochen [Gutachter] Blath, Noemi [Gutachter] Kurt, and Anton [Gutachter] Wakolbinger. "The effect of latency in population genetics / Adrián González Casanova Soberón ; Gutachter: Jochen Blath, Noemi Kurt, Anton Wakolbinger ; Jochen Blath, Noemi Kurt." Berlin : Technische Universität Berlin, 2016. http://d-nb.info/1156013100/34.
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Siska, Veronika. "Human population history and its interplay with natural selection." Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/284164.
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The complex demographic changes that underlie the expansion of anatomically modern humans out of Africa have important consequences on the dynamics of natural selection and our ability to detect it. In this thesis, I aimed to refine our knowledge on human population history using ancient genomes, and then used a climate-informed, spatially explicit framework to explore the interplay between complex demographies and selection. I first analysed a high-coverage genome from Upper Palaeolithic Romania from ~37.8 kya, and demonstrated an early diversification of multiple lineages shortly after the out-of-Africa expansion (Chapter 2). I then investigated Late Upper Palaeolithic (~13.3ky old) and Mesolithic (~9.7 ky old) samples from the Caucasus and a Late Upper Palaeolithic (~13.7ky old) sample from Western Europe, and found that these two groups belong to distinct lineages that also diverged shortly after the out of Africa, ~45-60 ky ago (Chapter 3). Finally, I used East Asian samples from ~7.7ky ago to show that there has been a greater degree of genetic continuity in this region compared to Europe (Chapter 4). In the second part of my thesis, I used a climate-informed, spatially explicit demographic model that captures the out-of-Africa expansion to explore natural selection. I first investigated whether the model can represent the confounding effect of demography on selection statistics, when applied to neutral part of the genome (Chapter 5). Whilst the overlap between different selection statistics was somewhat underestimated by the model, the relationship between signals from different populations is generally well-captured. I then modelled natural selection in the same framework and investigated the spatial distribution of two genetic variants associated with a protective effect against malaria, sickle-cell anaemia and β⁰ thalassemia (Chapter 6). I found that although this model can reproduce the disjoint ranges of different variants typical of the former, it is incompatible with overlapping distributions characteristic of the latter. Furthermore, our model is compatible with the inferred single origin of sickle-cell disease in most regions, but it can not reproduce the presence of this disorder in India without long-distance migrations.
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Tran, Tat Dat [Verfasser], Jürgen [Akademischer Betreuer] Jost, Jürgen [Gutachter] Jost, and Shun-ichi [Gutachter] Amari. "Information Geometry and the Wright-Fisher model of Mathematical Population Genetics / Tat Dat Tran ; Gutachter: Jürgen Jost, Shun-ichi Amari ; Betreuer: Jürgen Jost." Leipzig : Universitätsbibliothek Leipzig, 2012. http://d-nb.info/1238077277/34.
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Hechter, Eliana. "On genetic variants underlying common disease." Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:d883f20e-7dad-4216-8851-b006993832fd.
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Genome-wide association studies (GWAS) exploit the correlation in ge- netic diversity along chromosomes in order to detect effects on disease risk without having to type causal loci directly. The inevitable downside of this approach is that, when the correlation between the marker and the causal variant is imperfect, the risk associated with carrying the predisposing allele is diluted and its effect is underestimated. This thesis explores four different facets of this risk dilution: (1) estimating true effect sizes from those observed in GWAS; (2) asking how the context of a GWAS, including the population studied, the genotyping chip employed, and the use of im- putation, affects risk estimates; (3) assessing how often the best-associated SNP in a GWAS coincides with the causal variant; and (4) quantifying how departures from the simplest disease risk model at a causal variant distort the observed disease risk model. Using simulations, where we have information about the true risk at the causal locus, we show that the correlation between the marker and the causal variant is the primary driver of effect size underestimation. The extent of the underestimation depends on a number of factors, including the population in which the study is conducted, the genotyping chip employed, whether imputation is used, and the strength, frequency, and disease model of the risk allele. Suppose that a GWAS study is conducted in a European population, with an Affymetrix 6.0 genotyping chip, without imputation, and that the causal loci have a modest effect on disease risk, are common in the population, and follow an additive disease risk model. In such a study, we show that the risk estimated from the most associated SNP is very close to the truth approximately two-thirds of the time (although we predict that fine mapping of GWAS loci will infrequently identify causal variants with considerably higher risk), and that the best-associated variant is very often perfectly or nearly-perfectly correlated with, and almost always within 0.1cM of, the causal variant. However, the strong correlations among nearby loci mean that the causal and best-associated variants coincide infrequently, less than one-fifth of the time, even if the causal variant is genotyped. We explore ways in which these results change quantitatively depending on the parameters of the GWAS study. Additionally, we demonstrate that we expect to identify substantial deviations from the additive disease risk model among loci where association is detected, even though power to detect departures from the model drops off very quickly as the correlation between the marker and causal loci decreases. Finally, we discuss the implications of our results for the design and interpretation of future GWAS studies.
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Bhatt, Samir. "Statistical analysis of natural selection in RNA virus populations." Thesis, University of Oxford, 2010. http://ora.ox.ac.uk/objects/uuid:64341c38-f09e-48ed-84e8-7ab9f171a753.
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A key goal of modern evolutionary biology is the identification of genes or genome regions that have been targeted by natural selection. Methods for detecting natural selection utilise the information sampled in contemporary gene sequences and test for deviation from the null hypothesis of neutrality. One such method is the McDonald Kreitman test (MK test), which detects the the molecular 'footprint' left by natural selection by considering the frequency of observed mutations within the sampled population. In this thesis I investigate the applicability of the MK test to viral populations and develop several new methods based on the original MK test. In chapter 2, I use a combination of simulation and methodological improvements to show that the MK test can have low error when applied to analysis of RNA virus populations. Then, in chapter 3, I develop an extension of the MK test with the purpose of estimating rates of adaptive fixation for all genes of the human influenza A virus subtypes H1N1 and H3N2. My results are consistent with previous studies on selection in influenza virus populations, and provide a new perspective on the evolutionary dynamics of human influenza virus. In chapter 4 I develop a formal statistical framework based, on the MK test, for calculating the number of non neutral sites at any frequency range in the site frequency spectrum. In this framework, I introduce a new method for reconstructing the site frequency spectrum that incorporates sampling error and allows for the inclusion of prior knowledge. Using this new framework I show that the majority of nucleotide sites in hepatitis C virus sequences sampled during chronic infection represent deleterious mutations. Finally, in chapter 5 I use the generalised framework introduced in chapter 4 to develop a statistic for evaluating the deleterious mutation load of a population. I apply this test sequences that represent 96 RNA virus genes and show that my approach has comparable power to equivalent phylogenetic methods. In this thesis I have developed computationally efficient methods for analysis of genetic data from virus populations. It is my hope that these methods will become useful given the explosion in sequence data that has accompanied recent improvements in sequencing technology.
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Dilthey, Alexander Tilo. "Statistical HLA type imputation from large and heterogeneous datasets." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:1bca18bf-b9d5-4777-b58e-a0dca4c9dbea.
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An individual's Human Leukocyte Antigen (HLA) type is an essential immunogenetic parameter, influencing susceptibility to a variety of autoimmune and infectious diseases, to certain types of cancer and the likelihood of adverse drug reactions. I present and evaluate two models for the accurate statistical determination of HLA types for single-population and multi-population studies, based on SNP genotypes. Importantly, SNP genotypes are already available for many studies, so that the application of the statistical methods presented here does not incur any extra cost besides computing time. HLA*IMP:01 is based on a parallelized and modified version of LDMhc (Leslie et al., 2008), enabling the processing of large reference panels and improving call rates. In a homogeneous single-population imputation scenario on a mainly British dataset, it achieves accuracies (posterior predictive values) and call rates >=88% at all classical HLA loci (HLA-A, HLA-B, HLA-C, HLA-DQA1, HLA-DQB1, HLA-DRB1) at 4-digit HLA type resolution. HLA*IMP:02 is specifically designed to deal with multi-population heterogeneous reference panels and based on a new algorithm to construct haplotype graph models that takes into account haplotype estimate uncertainty, allows for missing data and enables the inclusion of prior knowledge on linkage disequilibrium. It works as well as HLA*IMP:01 on homogeneous panels and substantially outperforms it in more heterogeneous scenarios. In a cross-European validation experiment, even without setting a call threshold, HLA*IMP:02 achieves an average accuracy of 96% at 4-digit resolution (>=91% for all loci, which is achieved at HLA-DRB1). HLA*IMP:02 can accurately predict structural variation (DRB paralogs), can (to an extent) detect errors in the reference panel and is highly tolerant of missing data. I demonstrate that a good match between imputation and reference panels in terms of principal components and reference panel size are essential determinants of high imputation accuracy under HLA*IMP:02.
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Pereira, Renato Nunes. "Modelo hierárquico bayesiano na determinação de associação entre marcadores e QTL em uma população F2." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/11/11134/tde-25042012-161429/.
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O objetivo do mapeamento de QTL (Quantitative Trait Loci ) e identificar sua posição no genoma, isto e, identificar em qual cromossomo esta e qual sua localização nesse cromossomo, bem como estimar seus efeitos genéticos. Uma vez que as localizações dos QTL não são conhecidas a priori, marcadores são usados frequentemente para auxiliar no seu mapeamento. Alguns marcadores podem estar altamente ligados a um ou mais QTL e, dessa forma eles podem mostrar uma alta associação com a característica fenotípica. O efeito genético do QTL e os valores fenotípicos de uma característica quantitativa são normalmente descritos por um modelo linear. Uma vez que as localizações dos QTL não são conhecidas a priori, marcadores são utilizados para representá-los. Em geral, e utilizado um numero grande de marcadores. Esses marcadores são utilizados no modelo linear para proceder ao processo de associação; dessa forma o modelo especificado contem um numero elevado de parâmetros a serem estimados. No entanto, e esperado que muitos destes parâmetros sejam não significativos, necessitando de um tratamento especial. Na estimação bayesiana esse problema e tratado por meio da estrutura de distribuições a priori utilizada. Um parâmetro que e esperado assumir o valor zero (não significativo) e naturalmente especificado por meio de uma distribuição que coloque um peso maior no zero, encolhimento bayesiano. Neste trabalho e proposta a utilização de dois modelos que utilizam distribuições a priori de encolhimento. Um dos modelos esta relacionado com o uso da distribuição a priori Laplace (Lasso bayesiano) e o outro com a Horseshoe (Estimador Horseshoe). Para avaliar o desempenho dos modelos na determinação da associação entre marcadores e QTL, realizou-se um estudo de simulação. Foi analisada a associação entre marcadores e QTL utilizando três características fenotípicas: produção de grãos, altura da espiga e altura da planta. Comparou-se os resultados obtidos neste trabalho com analises feitas na literatura na detecção dos marcadores associados a essas características. A implementação computacional dos algoritmos foi feita utilizando a linguagem C e executada no pacote estatístico R. O programa implementado na linguagem C e apresentado e disponibilizado. Devido a interação entre as linguagens de programação C e R, foi possível executar o programa no ambiente R.The objective of the mapping of quantitative trait loci (QTL) is to identify its position in the genome, ie, identify which chromosome is and what is its location in the chromosome, as well as to estimate their genetic eects. Since the location of QTL are not known a priori, markers are often used to assist in it mapping. Some markers may be closely linked to one or more QTL, and thus they may show a strong association with the phenotypic trait. The genetic eect of QTL and the phenotypic values of a quantitative trait are usually described by a linear model. Since the QTL locations are not known a priori, markers are used to represent them. Generally is used a large number of markers. These markers are used in the linear model to make the process of association and thus the model specied contains a large number of parameters to be estimated. However, it is expected that many of these parameters are not signicant, requiring a special treatment. In Bayesian estimation this problem is treated through structure priori distribution used. A parameter that is expected to assume the value zero (not signicant) is naturally specied by means of a distribution that put more weight at zero, bayesian shrinkage. This paper proposes the use of two models using priori distributions to shrinkage. One of the models is related to the use of priori distribution Laplace (bayesian Lasso) and the other with Horseshoe (Horseshoe Estimator). To evaluate the performance of the models to determine the association between markers and QTL, we performed a simulation study. We analyzed the association between markers and QTL using three phenotypic traits: grain yield, ear height and plant height. We compared the results obtained in this study with analyzes in the literature on the detection of markers associated with these characteristics. The computational implementation of the algorithms was done using the C language and executed the statistical package R. The program is implemented in C languages presented and made available. Due to the interaction between the programming languages C and R, it was possible execute the program in the environment R.
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Gryspeirt, Aiko. "Impact des plantes Bt sur la biologie de Plodia interpunctella: évaluation de l'efficacité de la stratégie agricole "Haute dose - refuge" pour la gestion de la résistance des insectes ravageurs aux plantes Bt." Doctoral thesis, Universite Libre de Bruxelles, 2008. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210542.
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Commercialisées depuis 1996, les plantes génétiquement modifiées produisant une toxine insecticide (toxine Cry) dérivée de Bacillus thuringiensis et appelées plantes Bt ciblent certains Lépidoptères ou Coléoptères ravageurs. Au fil des ans, les surfaces cultivées en plantes Bt sont de plus en plus importantes et contrôlent de larges populations d'insectes. Pour limiter le risque de développement de populations résistantes, une stratégie agricole appelée 'Haute Dose / Zone Refuge' est actuellement recommandée aux Etats-Unis par l'Environmental Protection Agency. Cette stratégie préventive nécessite la plantation d'une 'zone refuge' composée de plantes non-Bt utilisables par le ravageur ciblé et plantée à proximité de la 'zone Bt' qui synthétise une haute dose de toxine Cry. Mon projet de recherche s’inscrit dans le cadre de l’évaluation de l'efficacité de cette stratégie et s’articule en deux phases :une phase expérimentale et une phase théorique. La première se concentre sur la caractérisation en laboratoire de l'impact des toxines Cry sur la biologie d'un ravageur. Cette phase constitue un support au volet théorique :la mise au point d’un modèle mathématique évaluant l'efficacité de la stratégie HD/R. L'originalité de ce projet repose entre autre sur l'interactivité entre ces deux volets.
Volet expérimental. Impact des toxines Cry sur la biologie de Plodia interpunctella. Nous évaluons séparément l'impact d'une gamme de concentrations de deux toxines Cry (CryXX et CryYY) sur une série de paramètres comportementaux et biologiques d'un insecte commun des denrées stockées: Plodia interpunctella (Hübner) (Lepidoptera :Pyralidae). Ces paramètres sont sélectionnés car leur variation pourrait avoir un impact sur l'efficacité de la stratégie HD/R dans le contrôle de la résistance. Il est donc pertinent de les quantifier pour intégrer dans le modèle des ordres de grandeur réalistes et générer des résultats qui ne sont pas uniquement basés sur des spéculations théoriques.
Volet théorique A. Efficacité de la stratégie HD/R pour des plantes Bt synthétisant une ou deux toxines simultanément. La stratégie 'HD/R' a été développée pour prévenir la résistance envers les plantes Bt synthétisant une seule toxine. Or, depuis 2003, de nouvelles variétés de coton Bt synthétisant simultanément deux toxines Cry sont commercialisées (BollgardII® et WidestrikeTM). Nous évaluons, grâce au modèle que nous avons développé, l'efficacité de cette stratégie lors d'une utilisation exclusive de plantes Bt synthétisant une ou deux toxines.
Volet théorique B. Impact du ralentissement du développement des insectes sur les plantes Bt sur l'efficacité de la stratégie HD/R. Le volet expérimental met en évidence un allongement de la durée du développement des larves se nourrissant sur une diète contaminée en toxine Cry. Ce ralentissement induit une séparation temporelle entre l'émergence des adultes de la zone Bt et de la zone refuge et perturbe une hypothèse principale de la stratégie HD/R: le croisement aléatoire entre adultes, indépendamment du génotype et de la zone d'origine. Dans ce troisième chapitre, nous étudions l'impact de la perturbation du croisement aléatoire sur l'efficacité de la stratégie HD/R. Nous testons également deux options pour optimiser la stratégie en cas d'asynchronie: l'utilisation de plantes Bt synthétisant une faible concentration en toxine (atténuant le décalage entre l'émergence des adultes) ou l'augmentation de la taille de la zone refuge (favorisant la survie des individus porteurs d'allèle de sensibilité et donc optimisant la dilution de la résistance à la génération suivante).
Ce travail s'intègre dans une problématique actuelle et utilise des outils de biologie théorique (théories de la dynamique et de la génétique des populations) ainsi que le développement d'un modèle mathématique. Il apporte des éléments de réponse et de réflexion sur l'optimisation de la gestion de la résistance des insectes mais c'est aussi une illustration de la complémentarité entre la biologie expérimentale et théorique.
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On the market since 1996, genetically modified plants synthesizing an insecticidal toxin (Cry toxin) stemmed from Bacillus thuringiensis, called Bt plants, target several insect pests (Lepidoptera or Coleoptera). Bt crops cover increasingly larger areas and control important pest populations The Insect Resistance Management Strategy (IRM) strategy currently recommended in the U.S.A. to limit the development of resistant populations is the High Dose / Refuge zone (HD/R) strategy. This pre-emptive strategy requires a refuge zone composed by non-Bt plants, usable by the target insect and in close proximity of the Bt zone synthesizing a high toxin concentration.
My research project contributes to the effectiveness assessment of this HD/R strategy. It is structured on two main parts: an experimental, and a theoretical section. The first part characterizes the impact of Cry toxins on the biology of an insect pest. It is the basis of the theoretical part: the implementation of a mathematical model, which evaluates the effectiveness of the HD/R strategy.
The originality of this project is based on the interactivity of these two components.
Experimental section. Impact of the Cry toxins on the biology of Plodia interpunctella. We assess the impact of a range of concentrations of two Cry toxins (CryXX et CryYY) on several behavioural and biological parameters of a common pest of stored products: Plodia interpunctella (Hübner) (Lepidoptera :Pyralidae). These parameters are selected because their variation could influence the effectiveness of a HD/R strategy. So, it is important to quantify these parameters so that realistic values can be integrated in our model. The results of the model are thus not based on theoretical assumptions alone.
Theoretical section A. Effectiveness of a HD/R strategy with Bt plants synthesizing one or two toxins. Initially, the HD/R strategy has been developed to limit the resistance towards Bt plants synthesizing one toxin. However, since 2003, new Bt cotton varieties synthesize two toxins simultaneously (BollgardII® et WidestrikeTM). We assess, with our model, the effectiveness of this strategy for Bt plants synthesizing one or two toxins.
Theoretical section B. Impact of the slowing down of the insect development reared on Bt plants on the effectiveness of the HD/R strategy. The experimental part demonstrates that larvae reared on a Bt diet have a protracted development duration. The consequence of this is a temporal separation between adult emergence in the two zones (Bt zone and refuge zone). This could affect the main assumption of the HD/R strategy, i. e. random mating independently of the genotype and of the native zone. In this third chapter, we study the impact of random mating disruption on the effectiveness of a HD/R strategy. We test two options to optimise the strategy in case of asynchrony: the use of Bt plants synthesizing a lower toxin concentration (limiting emergence asynchrony) or increasing the refuge zone size (favouring the survival of insect carrying one or two susceptible allele and thus optimising the dilution of resistance at the next generation).
This work is applied to a current issue. It uses some of the tools of theoretical biology (theories of population dynamics and population genetics) and develops a mathematical model. It provides some responses and some elements of thought about insect resistance management. It is also an illustration of the complementarity between experimental and theoretical biology.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished
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Blum, Michael G. B. "Statistique bayésienne et applications en génétique des populations." Habilitation à diriger des recherches, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00766196.
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Les approches statistiques en génétique des populations visent deux objectifs distincts qui sont la description des données et la possibilité d'inférer les processus évolutifs qui ont généré les patrons observés. Le premier chapitre de ce manuscrit décrit nos apports théoriques et méthodologiques concernant le calcul bayésien approché (Approximate Bayesian Computation) qui permet de réaliser l'objectif d'inférence des processus évolutifs. Je décris des résultats asymptotiques qui permettent de décrire des propriétés statistiques du calcul bayésien approché. Ces résultats mettent en évidence à la fois l'intérêt des méthodes dites avec ajustement qui reposent sur des équations de régression et aussi l'intérêt de réduire la dimension des descripteurs statistiques utilisés dans le calcul bayésien approché. Je présente ensuite une méthode originale de calcul bayésien approché qui permet de manière conjointe d'effectuer des ajustements et de réduire la dimension des descripteurs statistiques. Une comparaison des différentes méthodes de réduction de dimension clos le premier chapitre. Le deuxième chapitre est consacré à l'objectif de description des données et se place plus particulièrement dans un cadre spatial. Les méthodes statistiques proposées reposent sur le concept d'isolement par la distance qui est une forme particulière de l'autocorrélation spatiale où la corrélation entre individus décroit avec la distance. Une approche originale de krigeage nous permet de caractériser des patrons d'isolement par la distance non-stationnaire où la manière avec laquelle la corrélation entre individus décroit avec la distance dépend de l'espace. Une deuxième extension que nous proposons est celle d'isolement par la distance anisotrope que nous caractérisons et testons à partir d'une équation de régression. La conclusion de ce manuscrit met l'accent sur les problèmes d'interprétation des résultats statistiques, l'importance de l'échantillonnage et la nécessité de tester l'adéquation des modèles aux données. Je conclus par des perspectives qui se proposent de faire passer l'analyse statistique bayésienne à l'échelle des données massives produites en génétique.
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Brown, Samuel David James. "Molecular systematics and colour variation of Carpophilus species (Coleoptera: Nitidulidae) of the South Pacific." Diss., Lincoln University, 2009. http://hdl.handle.net/10182/1430.
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The sap beetle genus Carpophilus Stephens (Coleoptera: Nitidulidae) is a large genus consisting of over 200 species and are found worldwide. Several species are important pests of crops and stored products, and are frequently intercepted as part of biosecurity operations. The genus is poorly known taxonomically, and there are several species groups that are challenging to identify by morphological methods. In particular, two species found across the Pacific, C. maculatus Murray and C. oculatus Murray are frequently confused with each other. These two species are similar in size and colour, but differ primarily by the shape of the colour pattern on their elytra. However, this colour pattern is highly variable within both species, leading to ambiguity in the indentification of these species. Within C. oculatus, three subspecies have been described based on differences in the male genitalia and pronotal punctation: C. o. oculatus and C. o. gilloglyi Dobson are distributed widely across the Pacific, while C. o. cheesmani Dobson is known only from Vanuatu. A search of literature records and specimen collections revealed 32 species of Carpophilus recorded from the Pacific region. In addition there remain several unidentified specimens representing at least four species, two of which will be described subsequent to this research. A number of species recorded in the literature may have been misidentified, and these require further field collections and inspection of museum specimens to confirm their presence in the Pacific. To test the validity of the subspecies of C. oculatus, and its distinctiveness from C. maculatus, a phylogeny of available specimens of Carpophilus was inferred from one mitochondrial gene (cytochrome c oxidase subunit I (COI)), and two nuclear genes (28S ribsomal RNA (28S) and the internal transcribed spacer 2 (ITS2)). These data show large genetic distances between the three subspecies of C. oculatus of 7-12%. Given these distances are similar to those between other species in the genus, this indicates these subspecies may be elevated to full species. The data also consistently support a monophyletic relationship between C. o. oculatus and C. o. gilloglyi. Nuclear genes also support C. o. cheesmani as part of a clade with the other subspecies, but these relationships are unresolved in COI. Carpophilus maculatus was not supported as being the sister taxon of the C. o. oculatus and C. o. gilloglyi clade. Other relationships within Carpophilus were unresolved, possibly due to a combination of incomplete taxon sampling, and saturation of substitutions within the COI gene. Phylogeographic analysis of specimens collected from several localities within the range of C. oculatus showed that, with only one exception, there were no shared haplotypes between archipelagoes. This result suggests it may be possible to determine the provenence of intercepted specimens, providing further information regarding potential invasion pathways. A degree of geographic structuring was also present within C. o. gilloglyi, being separated into a western clade found in Fiji and Rotuma and an eastern clade distributed from the Kermadec Islands and Tonga to French Polynesia. This separation was most profound in COI data, with a mean pairwise distance between the clades of 7%. ITS2 data also demonstrates a degree of differentiation between the two clades, based on differences in the insertions and deletions between the clades. The variability in the shape and colour of the elytral pattern of C. oculatus was also investigated. Colour was quantified using a method based on Red-Green-Blue (RGB) colour values derived from digital photographs, while an outline analysis of the elytral pattern was conducted using elliptic Fourier analysis (EFA). Principal Components Analysis of the RGB values and EFA coefficients showed no clear separation between subspecies, nor were any trends correlated with host fruit or collection localities. Variation at all levels and all measures studied in this thesis show that this geographic region and this genus of beetles offer intruiging insights into speciation, biogeography and biological invasions. There is much scope for further research on the causes and consequences of this variation and the lives of these interesting insects.
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Viho, Agbélénko Goudjo. "Étude de modèles markoviens en génétique et calculs des temps d'absorption." Grenoble 1, 1996. http://www.theses.fr/1996GRE10121.
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Cette thèse porte sur l'étude de la modélisation de l'évolution, par des processus markoviens, de l'effectif d'un gène donné au cours des générations dans une population à taille limitée. Dans une première partie, nous faisons un recensement des différents types de chaînes de Markov homogènes utilisées dans la littérature pour une telle modélisation. Quand la taille de la population est grande, il est possible d'obtenir la convergence de ces chaînes de Markov vers des processus de diffusion homogènes grâce aux théorèmes de convergence qui font l'objet de la deuxième partie. La troisième partie de cette thèse est consacrée aux différentes méthodes de calcul des temps moyens avant absorption qui correspondent ici aux temps moyens avant disparition ou invasion complète du gène donné en partant de différentes conditions initiales. La quatrième partie propose une modélisation simple d'une maladie génétique, la drépanocytose, et l'influence du paludisme comme facteur de sélection sur l'évolution de cette maladie en Afrique
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Erfmeier, Alexandra. "Ursachen des Invasionserfolges von Rhododendron ponticum L. auf den Britischen Inseln Einfluss von Habitat und Genotyp /." Doctoral thesis, [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=975033476.
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Fischer, Stephan. "Modélisation de l'évolution de la taille des génomes et de leur densité en gènes par mutations locales et grands réarrangements chromosomiques." Phd thesis, INSA de Lyon, 2013. http://tel.archives-ouvertes.fr/tel-00924831.
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Bien que de nombreuses séquences génomiques soient maintenant connues, les mécanismes évolutifs qui déterminent la taille des génomes, et notamment leur part d'ADN non codant, sont encore débattus. Ainsi, alors que de nombreux mécanismes faisant grandir les génomes (prolifération d'éléments transposables, création de nouveaux gènes par duplication, ...) sont clairement identifiés, les mécanismes limitant la taille des génomes sont moins bien établis. La sélection darwinienne pourrait directement défavoriser les génomes les moins compacts, sous l'hypothèse qu'une grande quantité d'ADN à répliquer limite la vitesse de reproduction de l'organisme. Cette hypothèse étant cependant contredite par plusieurs jeux de données, d'autres mécanismes non sélectifs ont été proposés, comme la dérive génétique et/ou un biais mutationnel rendant les petites délétions d'ADN plus fréquentes que les petites insertions. Dans ce manuscrit, nous montrons à l'aide d'un modèle matriciel de population que la taille du génome peut aussi être limitée par la dynamique spontanée des duplications et des grandes délétions, qui tend à raccourcir les génomes même si les deux types de ré- arrangements se produisent à la même fréquence. En l'absence de sélection darwinienne, nous prouvons l'existence d'une distribution stationnaire pour la taille du génome même si les duplications sont deux fois plus fréquentes que les délétions. Pour tester si la sélection darwinienne peut contrecarrer cette dynamique spontanée, nous simulons numériquement le modèle en choisissant une fonction de fitness qui favorise directement les génomes conte- nant le plus de gènes, tout en conservant des duplications deux fois plus fréquentes que les délétions. Dans ce scénario où tout semblait pousser les génomes à grandir infiniment, la taille du génome reste pourtant bornée. Ainsi, notre étude révèle une nouvelle force susceptible de limiter la croissance des génomes. En mettant en évidence des comporte- ments contre-intuitifs dans un modèle pourtant minimaliste, cette étude souligne aussi les limites de la simple " expérience de pensée " pour penser l'évolution. Nous proposons un modèle mathématique de l'évolution structurelle des génomes en met- tant l'accent sur l'influence des différents mécanismes de mutation. Il s'agit d'un modèle matriciel de population, à temps discret, avec un nombre infini d'états génomiques pos- sibles. La taille de population est infinie, ce qui élimine le phénomène de dérive génétique. Les mutations prises en compte sont les mutations ponctuelles, les petites insertions et délétions, mais aussi les réarrangements chromosomiques induits par la recombinaison ectopique de l'ADN, comme les inversions, les translocations, les grandes délétions et les duplications. Nous supposons par commodité que la taille des segments réarrangés suit une loi uniforme, mais le principal résultat analytique est ensuite généralisé à d'autres dis- tributions. Les mutations étant susceptibles de changer le nombre de gènes et la quantité d'ADN intergénique, le génome est libre de varier en taille et en compacité, ce qui nous permet d'étudier l'influence des taux de mutation sur la structure génomique à l'équilibre. Dans la première partie de la thèse, nous proposons une analyse mathématique dans le cas où il n'y a pas de sélection, c'est-à-dire lorsque la probabilité de reproduction est identique quelle que soit la structure du génome. En utilisant le théorème de Doeblin, nous montrons qu'une distribution stationnaire existe pour la taille du génome si le taux de duplications par base et par génération n'excède pas 2.58 fois le taux de grandes délétions. En effet, sous les hypothèses du modèle, ces deux types de mutation déterminent la dynamique spontanée du génome, alors que les petites insertions et petites délétions n'ont que très peu d'impact. De plus, même si les tailles des duplications et des grandes délétions sont distribuées de façon parfaitement symétriques, leur effet conjoint n'est, lui, pas symétrique et les délétions l'emportent sur les duplications. Ainsi, si les tailles de délétions et de duplications sont distribuées uniformément, il faut, en moyenne, plus de 2.58 duplications pour compenser une grande délétion. Il faut donc que le taux de duplications soit quasiment trois fois supérieur au taux de délétions pour que la taille des génomes croisse à l'infini. L'impact des grandes délétions est tel que, sous les hypothèses du modèle, ce dernier résultat reste valide même en présence d'un mécanisme de sélection favorisant directement l'ajout de nouveaux gènes. Même si un tel mécanisme sélectif devrait intuitivement pousser les génomes à grandir infiniment, en réalité, l'influence des délétions va rapidement limiter leur accroissement. En résumé, l'étude analytique prédit que les grands réarrangements délimitent un ensemble de tailles stables dans lesquelles les génomes peuvent évoluer, la sélection influençant la taille précise à l'équilibre parmi cet ensemble de tailles stables. Dans la deuxième partie de la thèse, nous implémentons le modèle numériquement afin de pouvoir simuler l'évolution de la taille du génome en présence de sélection. En choisissant une fonction de fitness non bornée et strictement croissante avec le nombre de gènes dans le génome, nous testons le comportement du modèle dans des conditions extrêmes, poussant les génomes à croître indéfiniment. Pourtant, dans ces conditions, le modèle numérique confirme que la taille des génomes est essentiellement contrôlée par les taux de duplications et de grandes délétions. De plus, cette limite concerne la taille totale du génome et s'applique donc aussi bien au codant qu'au non codant. Nous retrouvons en particulier le seuil de 2.58 duplications pour une délétion en deçà duquel la taille des génomes reste finie, comme prévu analytiquement. Le modèle numérique montre même que, dans certaines conditions, la taille moyenne des génomes diminue lorsque le taux de duplications augmente, un phénomène surprenant lié à l'instabilité structurelle des grands génomes. De façon similaire, augmenter l'avantage sélectif des grands génomes peut paradoxalement faire rétrécir les génomes en moyenne. Enfin, nous montrons que si les petites insertions et délétions, les inversions et les translocations ont un effet limité sur la taille du génome, ils influencent très largement la proportion d'ADN non codant.
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Brink-Spalink, Rebekka. "Stochastic Models in Population Genetics: The Impact of Selection and Recombination." Doctoral thesis, 2015. http://hdl.handle.net/11858/00-1735-0000-0022-5F9A-D.
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Giorgi, Elena Edi. "A mathematical growth model of the viral population in early HIV-1 infections." 2011. https://scholarworks.umass.edu/dissertations/AAI3482705.
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In this thesis we develop a mathematical model to describe HIV-1 evolution during the first stages of infection (approximately within 40–60 days since onset), when one can assume exponential growth and random accumulation of mutations under a neutral drift. We analyze the Hamming distance (HD) distribution under different models (synchronous and asynchronous) in the absence of selection and recombination. In the second part of the thesis, we introduce recombination and develop a combinatorial approach to estimate the new HD distribution. We conclude describing a T statistic to test significance differences between the HD of two genetic samples, which we derive using U-statistics.
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Heuer, Benjamin. "Convergence of the Genealogy of the Spatial Cannings Model." Doctoral thesis, 2016. http://hdl.handle.net/11858/00-1735-0000-002B-7CA9-7.
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Groeneveld, Linn Fenna. "Species delimitation, phylogeography and population genetics of the endemic Malagasy dwarf lemurs (genus Cheirogaleus)." Doctoral thesis, 2008. http://hdl.handle.net/11858/00-1735-0000-000D-F23D-6.
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STUDENÁ, Lucie. "Aplikace matematických znalostí při výuce biologie." Master's thesis, 2018. http://www.nusl.cz/ntk/nusl-390973.
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The Theses deals with applications of mathematical knowledge in teaching biology and it is divided into four chapters. Each chapter is dedicated to another application: 1. Application of conditional probability in medical diagnostics, 2. Application of exponential function in population ecology, 3. Application of logic functions in mathematical modelation of neuron and 4. Aplication of binomial theorem and binomial distribution in genetics. Each application contains solved problems, a worksheet for students and a solution for each worksheet. Two application (1. and 2.) have been tested in teaching and as an assessment of my lessons students filled questionnaires. Results of these questionnaires are processed in the end of these chapters. This Thesis can be used in teaching or self-studying.
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Aston, Christopher Eric. "Statistical models for multilocus structures." Phd thesis, 1985. http://hdl.handle.net/1885/141088.
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Steinrücken, Matthias [Verfasser]. "Multiple merger coalescents and population genetic inference / vorgelegt von Matthias Steinrücken." 2009. http://d-nb.info/998939536/34.
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Ashander, Jaime. "Effects of parasite exchange between wild and farmed salmon." Master's thesis, 2010. http://hdl.handle.net/10048/1292.
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Human food production activities can dominate natural systems, altering ecological and evolutionary aspects of the environment. Disease-mediated interactions are of particular concern. For example, parasites may "spill-over'' from farms to wildlife. Parasites isolated on farms can evolve resistance to treatment chemicals , but "spill-back'' from wildlife to farms may alter evolutionary dynamics. Here, we consider exchange of parasites (Lepeophtheirus salmonis) between wild (Oncorhynchus gorbuscha) and farmed salmon. We derive and analyze discrete-time models that implicitly include wild salmon migrations. First, we extend a standard fisheries model to show parasite exchange affects "line-dominance'' in the population ecology of salmon. Second, we extend a classic population genetics model to show that wild salmon can theoretically provide an "ecosystem service'' by delaying the onset of chemical resistance in parasites on farms. This service, however is affected by a nonlinear feedback if farm parasites spill-back to affect wild salmon.Applied Mathematics
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Fehren-Schmitz, Lars. "Molekularanthropologische Untersuchungen zur präkolumbischen Besiedlungsgeschichte des südlichen Perus am Beispiel der Palpa-Region." Doctoral thesis, 2008. http://hdl.handle.net/11858/00-1735-0000-0006-AD06-F.
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Whale, John W. "Population genetic analysis of the black blow fly Phormia regina (Meigen) (Diptera: Calliphoridae)." Thesis, 2015. http://hdl.handle.net/1805/6722.
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Indiana University-Purdue University Indianapolis (IUPUI)The black blow fly, Phormia regina (Diptera: Calliphoridae), is a widely abundant fly autochthonous to North America. Like many other Calliphorids, P. regina plays a key role in several disciplines particularly in estimating post-mortem intervals (PMI). The aim of this work was to better understand the population genetic structure of this important ecological species using microsatellites from populations collected in the U.S. during 2008 and 2013. Additionally, it sought to determine the effect of limited genetic diversity on a quantitative trait throughout immature development; larval length, a measurement used to estimate specimen age. Observed heterozygosity was lower than expected at five of the six loci and ranged from 0.529-0.880 compared to expected heterozygosity that ranged from 0.512-0.980, this is indicative of either inbreeding or the presence of null alleles. Kinship coefficients indicate that individuals within each sample are not strongly related to one another; values for the wild-caught populations ranged from 0.033-0.171 and a high proportion of the genetic variation (30%) can be found among samples within regions. The population structure of this species does not correlate well to geography; populations are different to one another resulting from a lack of gene flow irrespective of geographic distance, thus inferring temporal distance plays a greater role on the genetic variation of P. regina. Among colonized samples, flies lost much of their genetic diversity, ≥67% of alleles per locus were lost, and population samples became increasingly more related; kinship coefficient values increased from 0.036 for the wild-caught individuals to 0.261 among the F10 specimens. Colonized larvae also became shorter in length following repeated inbreeding events, with the longest recorded specimen in F1 18.75 mm in length while the longest larva measured in F11 was 1.5 mm shorter at 17.25 mm. This could have major implications in forensic entomology, as the largest specimen is often assumed to be the oldest on the corpse and is subsequently used to estimate a postmortem interval. The reduction in length ultimately resulted in a greater proportion of individuals of a similar length; the range of data became reduced. Consequently, the major reduction in genetic diversity indicates that the loss in the spread of length distributions of the larvae may have a genetic influence or control. Therefore, this data highlights the importance when undertaking either genetic or development studies, particularly of blow flies such as Phormia regina, that collections of specimens and populations take place not only from more than one geographic location, but more importantly from more than one temporal event.
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Hao, Yangyang. "Computational modeling for identification of low-frequency single nucleotide variants." 2015. http://hdl.handle.net/1805/8891.
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Indiana University-Purdue University Indianapolis (IUPUI)Reliable detection of low-frequency single nucleotide variants (SNVs) carries great significance in many applications. In cancer genetics, the frequencies of somatic variants from tumor biopsies tend to be low due to contamination with normal tissue and tumor heterogeneity. Circulating tumor DNA monitoring also faces the challenge of detecting low-frequency variants due to the small percentage of tumor DNA in blood. Moreover, in population genetics, although pooled sequencing is cost-effective compared with individual sequencing, pooling dilutes the signals of variants from any individual. Detection of low frequency variants is difficult and can be cofounded by multiple sources of errors, especially next-generation sequencing artifacts. Existing methods are limited in sensitivity and mainly focus on frequencies around 5%; most fail to consider differential, context-specific sequencing artifacts. To face this challenge, we developed a computational and experimental framework, RareVar, to reliably identify low-frequency SNVs from high-throughput sequencing data. For optimized performance, RareVar utilized a supervised learning framework to model artifacts originated from different components of a specific sequencing pipeline. This is enabled by a customized, comprehensive benchmark data enriched with known low-frequency SNVs from the sequencing pipeline of interest. Genomic-context-specific sequencing error model was trained on the benchmark data to characterize the systematic sequencing artifacts, to derive the position-specific detection limit for sensitive low-frequency SNV detection. Further, a machine-learning algorithm utilized sequencing quality features to refine SNV candidates for higher specificity. RareVar outperformed existing approaches, especially at 0.5% to 5% frequency. We further explored the influence of statistical modeling on position specific error modeling and showed zero-inflated negative binomial as the best-performed statistical distribution. When replicating analyses on an Illumina MiSeq benchmark dataset, our method seamlessly adapted to technologies with different biochemistries. RareVar enables sensitive detection of low-frequency SNVs across different sequencing platforms and will facilitate research and clinical applications such as pooled sequencing, cancer early detection, prognostic assessment, metastatic monitoring, and relapses or acquired resistance identification.
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Mader, Felix. "Räumliche, GIS-gestützte Analyse von Linientransektstichproben." Doctoral thesis, 2007. http://hdl.handle.net/11858/00-1735-0000-0006-B626-D.
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