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Yeates, G. "Microbial population dynamics of the rhizosphere." Thesis, University of Oxford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334939.
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Huang, Shun. "Using Artificial Neural Networks to Predict One Year Population Mortality Rates." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-254974.
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Being able to predict mortality rates is the key factor in any pension or life insurance companies’ business model. Artificial Neural Networks are already being tested and implemented to predict mortality in the field of medical science, with recent studies showing promising results of their predictive power in one year mortality rates. Today, insurance companies in Sweden utilizes the Makeham curve to model and approximate mortality, traditionally with only age and sex being its input features. This study utilized artificial neural networks to model one year mortality rates that could otherwise be derived from the Makeham curve. Features other than sex and age were also included as a part of this study to introduce more features that could affect mortality rate. The network was successful at modelling the one year mortality rates and it was able to distinguish between age, sex and the newly introduced features. It yielded results that were on par with predictions made by the Swedish branch organization of the private insurance companies.<br>Att kunna förutspå dödlighet är en nyckelfaktor för pensionoch livförsäkringsföretagens affärsmodeller. Man har redan börjat tillämpa och testa artificiella neurala nätverk för att förutspå dödlighet inom medicinska studier. På senare tid har dessa påvisat lovande resultat gällande förutsägningsförmåga för ettårsdödlighet. Idag använder de svenska försäkringsföretagen Makehamkurvan för att modellera dödlighet, traditionellt sett med endast ålder och kön som indata. Artificiella neurala nätverk används i den här studien för att modellera ettårsdödlighet som annars kan härledas från Makehamkurvan. Utöver kön och ålder har även andra särdrag använts. Det visade sig att det neurala nätverket lyckades modellera ettårsdödlighet och kunde särskilja mellan ålder, kön och de nya särdragen. Resultatet var också i nivå med prediktionerna gjorda av Svensk Försäkring.
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Marshall, James Arthur Robert. "An investigation into kin selection and reciprocal cooperation in a viscous population." Thesis, De Montfort University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246514.
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Buckley, Raymond M. "Substrate associated recruitment of juvenile Sebastes in artificial reef and natural habitats in Puget Sound and the San Juan Archipelago, Washington /." Thesis, Connect to this title online; UW restricted, 1997. http://hdl.handle.net/1773/5373.
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Shringarpure, Suyash. "Statistical Methods for studying Genetic Variation in Populations." Research Showcase @ CMU, 2012. http://repository.cmu.edu/dissertations/117.
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The study of genetic variation in populations is of great interest for the study of the evolutionary history of humans and other species. Improvement in sequencing technology has resulted in the availability of many large datasets of genetic data. Computational methods have therefore become quite important in analyzing these data. Two important problems that have been studied using genetic data are population stratification (modeling individual ancestry with respect to ancestral populations) and genetic association (finding genetic polymorphisms that affect a trait). In this thesis, we develop methods to improve our understanding of these two problems.
For the population stratification problem, we develop hierarchical Bayesian models that incorporate the evolutionary processes that are known to affect genetic variation. By developing mStruct, we show that modeling more evolutionary processes improves the accuracy of the recovered population structure. We demonstrate how nonparametric Bayesian processes can be used to address the question of choosing the optimal number of ancestral populations that describe the genetic diversity of a given sample of individuals. We also examine how sampling bias in genotyping study design can affect results of population structure analysis and propose a probabilistic framework for modeling and correcting sample selection bias.
Genome-wide association studies (GWAS) have vastly improved our understanding of many diseases. However, such studies have failed to uncover much of the variation responsible for a number of common multi-factorial diseases and complex traits. We show how artificial selection experiments on model organisms can be used to better understand the nature of genetic associations. We demonstrate using simulations that using data from artificial selection experiments improves the performance of conventional methods of performing association. We also validate our approach using semi-simulated data from an artificial selection experiment on Drosophila Melanogaster.
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Eryilmaz, Kerem. "Bootstrapping Shared Vocabulary In A Population - Weighted Lists With Probabilistic Choice." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613691/index.pdf.
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Works on semiotic dynamics and language as a complex adaptive system in general has been an important lane of research over the last decade. In this study, the mean-field naming game model developed in the course of the pioneering research programme of Luc Steels and colleagues is modified to include probabilistic word choice based on weighted lists of words, instead of either deterministic or totally random word choice based on (ordered) sets of words. The parameters&rsquo<br>interaction and this interaction&rsquo<br>s effect on time of convergence of the system and size of individual lexicons over time are investigated. The classical model is found to be a
special case of this proposed model. Additionally, this model has more parameters and a larger state space which provides additional room for tweaking for time- or space-optimization of
the convergence process.
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Sanchez, Théophile. "Reconstructing our past ˸ deep learning for population genetics." Electronic Thesis or Diss., université Paris-Saclay, 2022. http://www.theses.fr/2022UPASG032.
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Avec l'explosion des technologies de séquençage, de plus en plus de données génomiques sont disponibles, ouvrant la voie à une connaissance approfondie des forces évolutives en œuvre et en particulier de l'histoire démographique des populations. Toutefois, extraire l'information intéressante de ces données massives de manière efficace reste un problème ouvert. Compte tenu de leurs récents succès en apprentissage statistique, les réseaux de neurones artificiels sont un candidat sérieux pour mener à bien une telle analyse. Ces méthodes ont l'avantage de pouvoir traiter des données ayant une grande dimension, de s'adapter à la plupart des problèmes et d'être facilement mis à l'échelle des moyens de calcul disponibles. Cependant, leur performance dépend fortement de leur architecture qui requiert d'être en adéquation avec les propriétés des données afin d'en tirer le maximum d'information. Dans ce cadre, cette thèse présente de nouvelles approches basées sur l'apprentissage statistique profond, ainsi que les principes permettant de concevoir des architectures adaptées aux caractéristiques des données génomiques. L'utilisation de couches de convolution et de mécanismes d'attention permet aux réseaux présentés d'être invariants aux permutations des haplotypes échantillonnés et de s'adapter à des données de dimensions différentes (nombre d'haplotypes et de sites polymorphes). Les expériences conduites sur des données simulées démontrent l'efficacité de ces approches en les comparant à des architectures de réseaux plus classiques, ainsi qu'à des méthodes issues de l'état de l'art. De plus, la possibilité d'assembler les réseaux de neurones à certaines méthodes déjà éprouvées en génétique des populations, comme l'approximate Bayesian computation, permet d'améliorer les résultats et de combiner leurs avantages. La praticabilité des réseaux de neurones pour l'inférence démographique est testée grâce à leur application à des séquences génomiques complètes provenant de populations réelles de Bos taurus et d'Homo sapiens. Enfin, les scénarios obtenus sont comparés aux connaissances actuelles de l'histoire démographique de ces populations<br>Constant improvement of DNA sequencing technology that produces large quantities of genetic data should greatly enhance our knowledge of evolution, particularly demographic history. However, the best way to extract information from this large-scale data is still an open problem. Neural networks are a strong candidate to attain this goal, considering their recent success in machine learning. These methods have the advantages of handling high-dimensional data, adapting to most applications and scaling efficiently to available computing resources. However, their performance dependents on their architecture, which should match the data properties to extract the maximum information. In this context, this thesis presents new approaches based on deep learning, as well as the principles for designing architectures adapted to the characteristics of genomic data. The use of convolution layers and attention mechanisms allows the presented networks to be invariant to the sampled haplotypes' permutations and to adapt to data of different dimensions (number of haplotypes and polymorphism sites). Experiments conducted on simulated data demonstrate the efficiency of these approaches by comparing them to more classical network architectures, as well as to state-of-the-art methods. Moreover, coupling neural networks with some methods already proven in population genetics, such as the approximate Bayesian computation, improves the results and combines their advantages. The practicality of neural networks for demographic inference is tested on whole genome sequence data from real populations of Bos taurus and Homo sapiens. Finally, the scenarios obtained are compared with current knowledge of the demographic history of these populations
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Luck, Gary. "Bird population responses and artificial nest predation at inherent and induced edges in the Murray Mallee, South Australia /." Title page, contents and abstract only, 1996. http://web4.library.adelaide.edu.au/theses/09AEVH/09aevhl941.pdf.
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Nilsson, Mikael. "Parameter Tuning Experiments of Population-based Algorithms." Thesis, Mittuniversitetet, Institutionen för informationsteknologi och medier, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-13836.
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In this study, three different algorithms are implemented to solve thecapacitated vehicle routing problem with and without time windows:ant colony optimization, a genetic algorithm and a genetic algorithmwith self-organizing map. For the capacitated vehicle routing problemthe Augerat et al’s benchmark problems were used and for the capaci-tated vehicle routing problem with time windows the Solomon’sbenchmark problems. All three algorithms were tuned over thirtyinstances per problem with the tuners SPOT and ParamILS. The tuningresults from all instances were combined to the final parameter valuesand tested on a larger set of instances. The test results were used tocompare the algorithms and tuners against each other. The ant colonyoptimization algorithm outperformed the other algorithms on bothproblems when considering all instances. The genetic algorithm withself-organizing map found more best known solutions than any otheralgorithm when using parameters, on the capacitated vehicle routingproblem. The algorithms performed well and several new best knownresults were discovered for the capacitated vehicle routing problem andnew best solutions found by heuristics were discovered for the 100customer Solomon problems. When comparing the tuners they bothworked well and no clear winner emerged.
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Drexler, Michael. "Population Biology, Ecology, and Ecosystem Contributions of the Eastern Oyster (Crassostrea virginica) from Natural and Artificial Habitats in Tampa Bay, Florida." Scholar Commons, 2011. http://scholarcommons.usf.edu/etd/3081.
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The objective of this project was to document the status of oysters, Crassostrea virginica, from non-reef habitats throughout Tampa Bay, Florida, and assess the ecosystem contributions of those populations relative to reef-dwelling oysters. The aspects of oyster ecology studied here include condition, prevalence and intensity of disease (Perkinsus marinus - dermo), reproductive activity (including stage, fecundity, and juvenile recruitment), adult oyster density, and the faunal community associated with the oysters.
The predominant source of variation was seasonal, with lesser contributions among sites, and in most cases, little or no effect of the habitat type. Oysters populations from each habitat recruit juvenile oysters, produce mature individuals, and contribute viable gametes at the same magnitude with similar seasonality. The associated faunal communities were also largely similar between habitats at any given site. Measures of oyster density, combined with estimates of the total available habitat, suggest that natural oyster reefs may represent only a small portion of the total oyster community in Tampa Bay, while oysters associated with mangrove habitats and seawalls are probably the most abundant in the bay. Additional mapping and quantification of these habitats would help to define their bay-wide ecosystem-services value. Restoration projects, though small in size relative to other habitats, do provide alternative and additional habitat with comparable value to other oyster-bearing habitats.
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Yedid, Gabriel. "Changing a bit at a time : patterns and mechanisms of microevolution and macroevolution in an electronic microcosm." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33047.
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While the use of microbial model systems in experimental evolution has made great contributions to our understanding of evolutionary processes, technological limitations and the problems of transparency they cause continue to inhibit their use in understanding even the most basic evolutionary phenomena. Conventional mathematical models are too constraining in that the range of genotypes and fitnesses must be designated at the outset, and so such models cannot be used to describe truly open-ended systems. In this thesis, I use Artificial Life technology to investigate patterns and mechanisms of evolution over short and long periods of time in a simulated chemostat-type system. The system may be rendered completely transparent, and is "open" in that genotypes with unique sequences and fitness arise unpredictably through mutation and selection.<br>The results demonstrate that Artificial Life technology is an open-ended, yet tractable system that may be used satisfactorily to investigate problems that he beyond the reach of current theory and biotechnology. (Abstract shortened by UMI.)
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Calderon-Vilca, Hugo D., William I. Wun-Rafael, and Roberto Miranda-Loarte. "Simulation of suicide tendency by using machine learning." IEEE Computer Society, 2018. http://hdl.handle.net/10757/624720.
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El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado.<br>Suicide is one of the most distinguished causes of death on the news worldwide. There are several factors and variables that can lead a person to commit this act, for example, stress, self-esteem, depression, among others. The causes and profiles of suicide cases are not revealed in detail by the competent institutions. We propose a simulation with a systematically generated dataset; such data reflect the adolescent population with suicidal tendency in Peru. We will evaluate three algorithms of supervised machine learning as a result of the algorithm C4.5 which is based on the trees to classify in a better way the suicidal tendency of adolescents. We finally propose a desktop tool that determines the suicidal tendency level of the adolescent.<br>Revisión por pares
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Dwyer, Ross Gordon. "Ecological and anthropogenic constraints on waterbirds of the Forth Estuary : population and behavioural responses to disturbance." Thesis, University of Exeter, 2010. http://hdl.handle.net/10036/117159.
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Disturbance from engineering works is an increasing problem in terrestrial and marine ecosystems throughout the world. Many reported declines in population size, breeding success and body condition have been diagnosed as the result of anthropogenic disturbance, however little is known about the effect of long-term disturbance from large-scale engineering works. Understanding the mechanisms by which animals respond to anthropogenic activities is fundamental to explaining interactions, and resolving potential conflicts between humans and wildlife. This thesis focuses on the factors affecting the habitat use and foraging decisions in wintering shorebirds and wildfowl. The first half of this thesis considers the direct and indirect impacts on waterbirds of a major engineering project in central Scotland; construction of the new Clackmannanshire Bridge at Kincardine-on-Forth. For individual bird species in close proximity to the bridge site, round-the-clock construction work had consequences ranging from neutral to considerably negative. Cormorant Phalacrocorax carbo declined in the area, probably as a result of the disturbance of an important low tide roost. Redshank Tringa totanus, previously abundant in the prey-rich areas adjacent to the construction site, were displaced into poorer areas for most of the construction period; where they may also have suffered from increased interference competition and elevated risk from raptorial predators. Some positive effects of industrial development were also revealed; radio-transmitters combined with tilt-switch posture sensors indicate that Redshank were able to capitalise on the improved nocturnal visibility in areas around Grangemouth docks to assist with foraging and predator detection. Evidence is presented that birds switched foraging strategy (from sight to touch feeding) depending on ambient light levels; whereby artificial light was used in a similar manner to moonlight to assist with prey detection. Redshank also avoided riverine areas at night that were used frequently by day, probably in response to an elevated threat from nocturnal predators. As the predator landscape changes from day into night, birds adopt different strategies to minimise the risk from nocturnal predators. It is clearly important, therefore, that information on nocturnal distributions is available to inform decisions on site management, especially where anthropogenic activity continues throughout the diel cycle. Behavioural decisions were shown to vary widely within a species depending on individual state, metabolic demands and previous exposure to human disturbance. Prey resources were shown to change dramatically over the course of a winter. In response to this decline, the home range of Redshank contracted over a winter season. Similarly, animals responded less and took greater risks in response to experimental disturbance events later in the winter than earlier in the winter, and on days when the temperature was lower. This effect was strongest for individuals occupying heavily disturbed areas, which were possibly already compensating for lost feeding time and a negative energy balance. The results were consistent with the hypothesis that those individuals that respond most obviously to human disturbance were those least likely to suffer fitness consequences. This is the opposite from what is commonly assumed when behaviour is used as an index of disturbance impacts, most notably in the use of flush distance in the design of wildlife buffer zones. In conclusion, this study demonstrated various negative impacts of disturbance, including local displacement, due to construction activity on overwintering waterbirds. It also revealed two key, but poorly understood, phenomena relating to mechanisms for coping with anthropogenic disturbance: routine utilisation of artificial light to extend night-time feeding opportunities amongst Redshank and an adaptive flexibility in escape responses across a range of species under varying conditions of risk.
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Gonçalves, Reinaldo Bellini. "Development and validation of new methods of distribution of initial population on genetic algorithms for the problem of protein-ligand docking." Laboratório Nacional de Computação Científica, 2008. http://www.lncc.br/tdmc/tde_busca/arquivo.php?codArquivo=154.
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The methods of protein-ligand docking are computational methods usedto predict the mode of binding of molecules into drug candidates for its receptor. The docking allows tests of hundreds of compounds in ashort space of time, assisting in the discovery of new drug candidates. The great complexity that involves the binding of protein-ligand complex, makes the problem of docking computationally difficult to be solved. In this work, we used the Genetic Algorithms which is a technique of optimization based on the theory of biological evolution of Darwin. The proposed algorithm was implemented and tested initially by Camila S. de Magalhães in her doctoral thesis, with the Group of Molecular Modeling of Biological Systems at LNCC, with a range of 5 ligands of HIV-1 protease. It was built a new set used for test with 49 structures with several physico-chemical properties, distributed in 22 different families of protein, allowing for a broader test of the algorithm It was conducted a detailed study of the dependence of the genetic algorithm in relation to the distribution of its initial population and it was also investigated ways more efficient and robust to generate the same. Among these, the proposal to distribute the initial population based on the coordinates of individuals of lower energy in the population (proposal 5), it is very promising. This distribution has allowed the algorithm to obtain good results, finding solutions of lower energy in the population very close to experimental structure optimized, without having specific information about the experimental structure. This fact is very important, because the algorithm makes it more realistic in view that in the rational design of drugs, it has not the trial structure.<br>Os métodos de docking proteína-ligante, são métodos computacionais usados para predizer o modo de ligação de moléculas candidatas a fármaco em seu receptor. O docking permite o teste de centenas de compostos em um curto espaço de tempo, auxiliando na descoberta de novos candidatos a fármacos. A grande complexidade que envolve a ligação do complexo ligante-proteína, torna o problema de docking difícil de ser resolvido computacionalmente. Neste trabalho, são usados os Algoritmos Genéticos, que são uma técnica de otimização baseada na teoria da evolução biológica de Darwin. O algoritmo proposto foi implementado e testado inicialmente por Camila S. de Magalhães em sua tese de doutorado, junto ao Grupo de Modelagem Molecular de Sistemas Biológicos do LNCC, com um conjunto de 5 ligantes de HIV-1 protease.
Foi construido um novo conjunto utilizado para teste, agora com 49 estruturas com propriedades físico-químicas diversas, distribuidos em 22 famílias distintas de proteínas, permitindo um teste mais amplo do algoritmo. Foi realizado um estudo aprofundado sobre a dependência do Algoritmo Genético em relação à distribuição da sua população inicial e investigou-se formas mais eficientes e robustas de gerar a mesma. Dentre estas, a proposta de distribuir a população inicial baseada nas coordenadas dos indivíduos de menor energia na população (proposta 5), é muito promissora. Esta distribuição permitiu o algoritmo obter bons resultados, encontrando soluções de menor energia na população muito próximas a estrutura experimental otimizada, sem possuir informações específicas sobre a estrutura experimental. Este fato é muito importante, pois torna o algoritmo mais realista, tendo em vista que no desenho racional de fármacos real não se dispoe da estrutura experimental.
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Honnen, Ann-Christin [Verfasser]. "Evolutionary implications of artificial night-time lighting for the mosquito Culex pipiens : insights from genetics, physiology, behaviour and population structure / Ann-Christin Honnen." Berlin : Freie Universität Berlin, 2015. http://d-nb.info/1065670257/34.
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Ribeiro, Zulene Antônio [UNESP]. "Dieta artificial e metodologia de criação massal para o bem-estar de Helicoverpa armigera." Universidade Estadual Paulista (UNESP), 2017. http://hdl.handle.net/11449/148902.
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Previous issue date: 2017-02-03<br>A partir de estudos biológicos de Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), objetivou-se neste trabalho selecionar uma dieta artificial que possa melhor suprir as exigências nutricionais requeridas pelo inseto e estabelecer uma metodologia de criação massal de H. armigera em laboratório que forneça condições estruturais satisfatórias para seu desenvolvimento larval e desempenho das funções reprodutivas, assim por meio de boas práticas de produção proporcionar o bem-estar aos insetos. No estudo com dieta artificial foram medidos parâmetros de desenvolvimento, índices nutricionais e índices populacionais em H. armigera alimentada em quatro dietas artificiais utilizadas para a criação de outros lepidópteros. Os resultados indicaram que H. armigera foi capaz de completar o ciclo de vida nas quatro dietas, entretanto, com alterações no seu desenvolvimento dependendo do alimento ingerido na fase larval. Em condições nutricionais favoráveis, os insetos potencializaram a eficiência de utilização das dietas, com menor consumo e alta eficiência de conversão do alimento ingerido e digerido para ganho de biomassa, resultando em insetos mais vigorosos. Por outro lado, em condições menos favoráveis, as lagartas de H. armigera tentaram compensar a menor adequação nutricional modificando seu comportamento em relação à tomada do alimento, aumentando a ingestão da dieta; contudo, esse esforço resultou em maior gasto de energia no metabolismo, com baixa eficiência na conversão do alimento ingerido e digerido. A dieta artificial desenvolvida para Anticarsia gemmatalis Hübner (Lepidoptera: Erebidae) foi adequada ao desenvolvimento biológico de H. armigera, porém, a modificação realizada nesta dieta promoveu excelente desenvolvimento do inseto, com elevados índices populacionais e nutricionais, e sem decréscimo no vigor e potencial reprodutivo, sendo a mais indicada para criação massal de H. armigera. Quanto à metodologia de criação, este estudo visou abordar os principais desafios enfrentados na criação de H. armigera e identificar os processos de criação mais eficientes para a produção de insetos com desenvolvimento uniforme, e com quantidade e qualidade suficiente para serem utilizados em pesquisas básicas quanto aplicadas. Os efeitos no desenvolvimento larval de H. armigera foram analisados em condições de diferentes densidades, recipientes e formas de disponibilidade e quantidade de alimento. Para os adultos, três tamanhos de gaiolas e densidades de casais foram analisados. Os resultados indicaram alterações nos parâmetros biológicos de H. armigera em função das condições oferecidas para seu desenvolvimento nas fases larval e adulta. A sobrevivência e a fertilidade de H. armigera foram diretamente relacionadas com a densidade e o tamanho da gaiola de criação. Espera-se que os resultados obtidos nesse trabalho possam contribuir para o conhecimento científico e fornecer subsídios para o desenvolvimento de estudos que contribuam com o Manejo Integrado de H. armigera em diversas culturas hospedeiras.<br>From the biological studies of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), the objectives of this study were to select an artificial diet that could meet its nutritional requirements and establish a methodology of mass rearing in the laboratory that provides satisfactory structural conditions for larval development and reproductive performance of H. armigera, thus through good production practices to provide welfare to insects. In the study with artificial diet were measured developmental parameters, nutritional and population indices on H. armigera fed on four artificial diets used for rearing of other lepidopteran. The results indicated that H. armigera was able to complete the life cycle in the four diets, however, with changes in its development depending on the food ingested in the larval stage. In favorable nutritional conditions the insects increased the efficiency of diet utilization, with lower consumption and high conversion efficiency of ingested and digested food for biomass gain, resulting in more vigorous insects. On the other hand, under less favorable conditions, H. armigera larvae tried to compensate for the lower nutritional adequacy by modifying their behavior in relation to food intake, increasing the dietary intake; however, this effort resulted in increased energy expenditure on metabolism, with low efficiency in the conversion of ingested and digested food. The artificial diet developed for Anticarsia gemmatalis Hübner (Lepidoptera: Erebidae) was adequate for H. armigera development, but the modification made on this diet provided an excellent development of the insect, with high population and nutritional indices, and without decreasing vigor and reproductive potential, being the most indicated for H. armigera mass rearing. Regarding the rearing methodology, this study sought to address the main challenges faced in the rearing of H. armigera and to identify the most efficient rearing processes for the production of insects with uniform development, and with sufficient quantity and quality to be used in basic and applied research. The effects on H. armigera larval development were analyzed under conditions of different densities, containers, forms of availability and quantity of food. For the adults three sizes of cages and densities of couples were analyzed. Results indicated alterations in the biological parameters of H. armigera as a function of the conditions offered for the development of the larvae and adults. Survival and fertility of H. armigera were directly related to the density and size of the cage. It is expected that the results obtained in this work can contribute to scientific knowledge and provide subsidies for the development of studies that contribute to Integrated Pest Management.
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Lye, Gillian C. "Nesting ecology, management and population genetics of bumblebees : an integrated approach to the conservation of an endangered pollinator taxon." Thesis, University of Stirling, 2009. http://hdl.handle.net/1893/2086.
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Bumblebees have shown both long and short-term declines throughout their range. These declines may be attributed to a range of factors including changes in land use, alterations in climatic conditions and species introductions. However, management strategies for bumblebee conservation often focus on provision of summer forage resources and other factors are frequently overlooked. Provision of spring forage and nesting sites for bumblebee queens are rarely considered, though colony foundation and early colony growth are two of the most sensitive stages in bumblebee life history. Here, the efficacy of certain agri-environment prescriptions for providing spring forage and nest sites for bumblebees is assessed, highlighting a need for specific schemes targeted towards the provision of these vital resources in the rural environment. The nesting ecology of bumblebees is poorly understood because wild colonies are difficult to locate. However, a greater knowledge of the colony-level effects of environmental change is crucial to understanding bumblebee declines. Attracting bumblebee queens to nest in artificial domiciles could provide a valuable tool for studying colony-level responses. However, domicile trials and the findings of a literature review presented here demonstrate that this approach may be largely impractical for use in the UK. Conversely, a nationwide public bumblebee nest survey produced numerous data regarding nest site preferences among bumblebee species and also demonstrated that citizen science may also provide a sensitive method for detecting declines in currently common bumblebee species. An understanding of the ecology of species interactions and coexistence can provide valuable insights into factors that may influence declines. Data presented here suggest that coexistence between some bumblebee species may be maintained by resource partitioning based on diel activity patterns that are linked to species-specific environmental tolerances. If this is the case, the potential role of climate change in bumblebee declines may be severely underestimated. There is also increasing evidence that genetic factors may play a role in bumblebee losses, accelerating declines of small, fragmented populations as a result of reduction in genetic diversity and inbreeding depression. Here, the feasibility of reintroducing British B. subterraneus (now extinct in the UK) from New Zealand into England is assessed using population genetic techniques. The findings suggest that the population history of B. subterraneus in New Zealand has resulted in a dramatic loss of genetic diversity and high genetic divergence from the original UK population, suggesting that it may not be a suitable for use in the reintroduction attempt. This work draws together some understudied aspects of bumblebee ecology with a particular focus on nest site requirements, availability of spring forage, mechanisms of avoidance of inter-specific competition and population genetic processes. The potential role of these in bumblebee declines is considered and new data relevant to the conservation of these important species is presented. It is hoped that this work will inform future management strategies for bumblebee conservation, highlight areas in need of further study and provide a sound starting point for future research in these areas.
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Pianucci, Marcela Navarro. "Uma proposta para a obtenção da população sintética através de dados agregados para modelagem de geração de viagens por domicílio." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/18/18143/tde-24102016-154347/.
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A estimativa de viagens por domicílio é fundamental para a tomada de decisões relativas ao planejamento urbano e de transportes. Em geral, a obtenção destas informações é por meio de modelos tradicionais como o modelo clássico de quatro etapas, e a primeira etapa do modelo é a geração de viagens. Entretanto, modelos clássicos apresentam inúmeras falhas, muitas delas relacionadas a suposições prévias matemáticas (normalidade ou continuidade da variável dependente). Desta forma, surge a necessidade de testar outras técnicas de modo a minimizar as falhas apresentadas pelos modelos clássicos e utilizá-las como uma ferramenta auxiliar, como por exemplo, as Redes Neurais Artificiais (RNAs), que podem ser aplicáveis na modelagem de problemas complexos e não lineares na área de engenharia de transportes, pois apresentam capacidade de aprendizagem, adaptação e generalização. Assim, para estimar viagens por domicílio, seja pela modelagem tradicional ou pela modelagem RNA são necessários dados desagregados dos domicílios, incluindo dados dos indivíduos, como as atividades diárias que exerce me dados sócio demográficos, etc. Esses dados são geralmente obtidos por uma Pesquisa O/D, que fornece um banco de dados detalhado sobre o comportamento de viagem da população de uma cidade. No entanto, a maioria das cidades enfrenta problemas para a aquisição desses dados, uma vez que este tipo de pesquisa possui alto custo de preparação, execução, processamento e análise. Portanto, percebe-se a necessidade de novos métodos que forneçam dados confiáveis e com baixo custo, para estimar a demanda por viagens, capazes de gerar resultados com rapidez, qualidade e acurácia e sem a necessidade dos dados provenientes de uma Pesquisa O/D. Devido a dificuldade de aquisição de dados desagregados, foi proposto neste trabalho, a geração da população sintética com dados agregados a partir da aplicação do Método Monte Carlo. Este trabalho tem por objetivo gerar uma população sintética baseada em dados censitários agregados e testar a adequabilidade das RNAs para estimar viagens por domicílio. Neste estudo, a modelagem tradicional foi utilizada para comparar nos resultados obtidos com a modelagem RNA, pois o objetivo não foi checar minuciosamente a qualidade dos modelos lineares, e sim, testar a adequabilidade das RNAs para estimar viagens por domicílio. A abordagem tradicional se baseou em um modelo de regressão linear enquanto que a abordagem de redes neurais consistiu da rede perceptron multi camadas. Na execução do trabalho foram calibrados quatro modelos (dois de cada abordagem) com os dados desagregados da Pesquisa O/D e foram comparados os resultados obtidos de cada abordagem. Ao final do trabalho, foi possível escolher o modelo mais adequados de cada abordagem e em seguida, foram utilizados para prever viagens por domicílio com os dados obtidos pela população sintética. Os resultados indicaram que 70% das variáveis obtidas na população sintética foram consideradas aptas para o estudo e que a estimativa de viagens por domicílio da população sintética obtida em ambos os modelos (Modelo 3-RNA) e (Modelo 4-RLM) obtiveram uma boa previsão, ou seja, mais de 70% das viagens por domicílio da população sintética foram consideradas válidas. Isso demonstrou que, o uso de da modelagem RNA é uma técnica alternativa eficiente e promissora na área de planejamento de transportes, especificamente para a previsão de viagens por domicílio.<br>The estimated number of household travels is essential in the decision-making process related to urban and transportation planning. Usually, this information is obtained through traditional models, such as four-step classic model, for example, which has trip generation as a first step. However, classic models feature numerous failures. Many of these failures are related to mathematical prior assumptions (normality or continuity of the dependent variable). Thus, it is important to test other techniques in order to reduce the failures and use these techniques as an auxiliary tool, i.e. Artificial Neural Networks (ANN). ANN are applicable in the modeling of complex and nonlinear transportation problems, due to its learning, adaptation and generalization capacities. Thus, to estimate the number of household travel, either by traditional or by ANN models, it is required disaggregated data of the households. It might include information of individuals, as daily activities and sociodemographic information. Usually, these data are obtained by a O/D survey, which provides a detailed database of the population travel behavior of the city. However, the obtainment of this information leads to high costs of preparation, execution, processing and analysis of the data. Thus, most cities have faced problems to attain this information. Therefore, new methods of estimation providing reliable data and low cost, are required. It will enable to estimate the demand of travel, rapidly with quality and accuracy, without the need of data provided through an O/D survey. Due to the difficulty of acquiring disaggregated data, this study proposes the generation of synthetic population through aggregated data by applying the method of Monte Carlo. This study aims to generate a synthetic population based on aggregated census data, and test the suitability of ANN to estimate the number of household travels. Since the aim was not thoroughly check the quality of linear models, instead, test the suitability of ANN to estimate the number of household travels, obtained results of traditional and ANN models were compared. The traditional approach was based on a linear regression while the neural network consisted of Multilayer Perceptron network. Four models (two of each approach) were proposed and calibrated with disaggregated data of an O/D Survey. Then, the results were compared. It enabled to choose the most appropriate model of each approach. Hence, these models were used to forecast the number of household travels, using the data obtained by the synthetic population proposed. The results indicated that 70% of the variables obtained through the synthetic population, were considered suitable for the study. Besides, the estimated number of household travels of the synthetic population obtained for both models (Model 3-RNA and 4-MLR model) presented a good forecast, indicating that more than 70% of household travels of the synthetic population were considered valid. Finally, it is concluded that the use of ANN modeling is an effective and promising alternative technique in the transportation-planning field, specifically to forecast the number of household travels.
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Pathak, Amit. "Forecasting Models to Predict EQ-5D Model Indicators for Population Health Improvement." Ohio University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1480959312370497.
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Trębicki, Piotr. "Characterisation of the tritrophic interactions between tobacco yellow dwarf virus, its vector and host-plants." Thesis, Queensland University of Technology, 2010. https://eprints.qut.edu.au/39550/1/Piotr_Tr%C4%99bicki_Thesis.pdf.
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Tobacco yellow dwarf virus (TbYDV, family Geminiviridae, genus Mastrevirus) is an economically important pathogen causing summer death and yellow dwarf disease in bean (Phaseolus vulgaris L.) and tobacco (Nicotiana tabacum L.), respectively. Prior to the commencement of this project, little was known about the epidemiology of TbYDV, its vector and host-plant range. As a result, disease control strategies have been restricted to regular poorly timed insecticide applications which are largely ineffective, environmentally hazardous and expensive. In an effort to address this problem, this PhD project was carried out in order to better understand the epidemiology of TbYDV, to identify its host-plant and vectors as well as to characterise the population dynamics and feeding physiology of the main insect vector and other possible vectors. The host-plants and possible leafhopper vectors of TbYDV were assessed over three consecutive growing seasons at seven field sites in the Ovens Valley, Northeastern Victoria, in commercial tobacco and bean growing properties. Leafhoppers and plants were collected and tested for the presence of TbYDV by PCR. Using sweep nets, twenty-three leafhopper species were identified at the seven sites with Orosius orientalis the predominant leafhopper. Of the 23 leafhopper species screened for TbYDV, only Orosius orientalis and Anzygina zealandica tested positive. Forty-two different plant species were also identified at the seven sites and tested. Of these, TbYDV was only detected in four dicotyledonous species, Amaranthus retroflexus, Phaseolus vulgaris, Nicotiana tabacum and Raphanus raphanistrum. Using a quadrat survey, the temporal distribution and diversity of vegetation at four of the field sites was monitored in order to assess the presence of, and changes in, potential host-plants for the leafhopper vector(s) and the virus. These surveys showed that plant composition and the climatic conditions at each site were the major influences on vector numbers, virus presence and the subsequent occurrence of tobacco yellow dwarf and bean summer death diseases. Forty-two plant species were identified from all sites and it was found that sites with the lowest incidence of disease had the highest proportion of monocotyledonous plants that are non hosts for both vector and the virus. In contrast, the sites with the highest disease incidence had more host-plant species for both vector and virus, and experienced higher temperatures and less rainfall. It is likely that these climatic conditions forced the leafhopper to move into the irrigated commercial tobacco and bean crop resulting in disease. In an attempt to understand leafhopper species diversity and abundance, in and around the field borders of commercially grown tobacco crops, leafhoppers were collected from four field sites using three different sampling techniques, namely pan trap, sticky trap and sweep net. Over 51000 leafhopper samples were collected, which comprised 57 species from 11 subfamilies and 19 tribes. Twentythree leafhopper species were recorded for the first time in Victoria in addition to several economically important pest species of crops other than tobacco and bean. The highest number and greatest diversity of leafhoppers were collected in yellow pan traps follow by sticky trap and sweep nets. Orosius orientalis was found to be the most abundant leafhopper collected from all sites with greatest numbers of this leafhopper also caught using the yellow pan trap. Using the three sampling methods mentioned above, the seasonal distribution and population dynamics of O. orientalis was studied at four field sites over three successive growing seasons. The population dynamics of the leafhopper was characterised by trimodal peaks of activity, occurring in the spring and summer months. Although O. orientalis was present in large numbers early in the growing season (September-October), TbYDV was only detected in these leafhoppers between late November and the end of January. The peak in the detection of TbYDV in O. orientalis correlated with the observation of disease symptoms in tobacco and bean and was also associated with warmer temperatures and lower rainfall. To understand the feeding requirements of Orosius orientalis and to enable screening of potential control agents, a chemically-defined artificial diet (designated PT-07) and feeding system was developed. This novel diet formulation allowed survival for O. orientalis for up to 46 days including complete development from first instar through to adulthood. The effect of three selected plant derived proteins, cowpea trypsin inhibitor (CpTi), Galanthus nivalis agglutinin (GNA) and wheat germ agglutinin (WGA), on leafhopper survival and development was assessed. Both GNA and WGA were shown to reduce leafhopper survival and development significantly when incorporated at a 0.1% (w/v) concentration. In contrast, CpTi at the same concentration did not exhibit significant antimetabolic properties. Based on these results, GNA and WGA are potentially useful antimetabolic agents for expression in genetically modified crops to improve the management of O. orientalis, TbYDV and the other pathogens it vectors. Finally, an electrical penetration graph (EPG) was used to study the feeding behaviour of O. orientalis to provide insights into TbYDV acquisition and transmission. Waveforms representing different feeding activity were acquired by EPG from adult O. orientalis feeding on two plant species, Phaseolus vulgaris and Nicotiana tabacum and a simple sucrose-based artificial diet. Five waveforms (designated O1-O5) were observed when O. orientalis fed on P. vulgaris, while only four (O1-O4) and three (O1-O3) waveforms were observed during feeding on N. tabacum and the artificial diet, respectively. The mean duration of each waveform and the waveform type differed markedly depending on the food source. This is the first detailed study on the tritrophic interactions between TbYDV, its leafhopper vector, O. orientalis, and host-plants. The results of this research have provided important fundamental information which can be used to develop more effective control strategies not only for O. orientalis, but also for TbYDV and other pathogens vectored by the leafhopper.
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Curtolo, Maisa. "Desequilíbrio de ligação, análise de associação genômica ampla e sinais de seleção em soja." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/11/11137/tde-01082018-104635/.
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Com a disponibilidade de tecnologias de genotipagem robustas, fornecendo milhares de marcadores moleculares a um baixo custo por amostra, tornou-se mais acessível escanear o genoma todo. Logo, as abordagens de mapeamento associativo, baseado no cálculo do desequilíbrio de ligação, e a busca de regiões do genoma que apresentam sinais de seleção foram favorecidas. Essas ferramentas apresentam um grande potencial a ser explorado em programas de melhoramento de soja, auxiliando na obtenção de informações valiosas em relação à arquitetura genética dos caracteres de interesse agronômico e à dinâmica dos processos de seleção. Portanto, os objetivos deste estudo foram: (i) verificar os efeitos da relação genética entre genótipos no desequilíbrio de ligação; (ii) obter informações em relação a arquitetura genética para dez caracteres por meio da abordagem de mapeamento associativo; e (iii) identificar regiões sob seleção diferencial em uma população representada por cultivares brasileiras comparadas a de uma população de genótipos exóticos de diferentes origens geográficas. Para isto, 95 genótipos de soja foram genotipados utilizando a plataforma da Affymettrix (180 K Axiom® Soybean Genotyping Array). O efeito da estrutura populacional sobre DL foi investigado utilizando como correções as matrizes resultantes do software STRUCTURE, DAPC, PCA e a matriz de parentesco. Para o mapeamento associativo, os genótipos foram fenotipados para dez caracteres. Foram realizadasvárias abordagens para detecção de sinais de seleção: estimação da diferenciação populacional nas regiões do genoma por meio do índice de fixção (FST) e cross-population composite likelihood ratio test (XP-CLR); identificação de regiões do genoma com redução de diversidade nucleotídica (μ); e a presença de blocos de haplótipos. Ao utilizar medidas de correções para estimação do DL no genoma da soja observamos a influência da estrutura da população e do parentesco nos padrões de DL. Pelo mapeamento associativo, foram identificados 181 marcadores associados para dez caracteres avaliados em soja. Além disso, foi verificada a complexa interação entre regiões envolvidas no controle de caracteres quantitativos (QTL) e ambientes. Regiões diferencialmente selecionadas foram identificadas entre a população de genótipos brasileiros e de materiais de origens diversas, demonstrando que essas passaram por processos de seleção divergente.<br>The availability of robust genotyping technologies providing thousands of markers with a low-cost per sample, whole-genome scans are becoming more accessible. Hence, associative mapping approaches, based on the calculation of linkage disequilibrium (LD), and the detection of signals of selection were favored. These tools have a great potential to be explored in soybean breeding programs, helping to obtain valuable information about the genetic architecture of the characters of agronomic interest and of the dynamics of selection processes. Therefore, the objectives of this study were: (i) to verify the effects of the genetic relationship among genotypes on soybean linkage disequilibrium; (ii) to obtain information about the genetic architecture in ten soybean traits with an association mapping approach; and (iii) to identify regions under differential selection between a population represented by Brazilian cultivars compared to a population of exotic genotypes from different geographic origins. For this, 95 soybean genotypes were genotyped using an Affymetrix (180 K Axiom® Soybean Genotyping Array) platform. The effect of the population structure on LD was investigated using as corrections the matrices resulting from the software STRUCTURE, DAPC, PCA and a kinship matrix. We phenotyped ten soybean traits in order to carry the association mapping. Several approaches were carried aiming to detect selection signals: estimation of population genetic differentiation in the genomic regions with fixation index (FST) and cross-population composite likelihood ratio test (XP-CLR); identification of genomic regions with reduced nucleotide diversity (μ); and the presence of haplotype blocks.Using the LD corrections, it was showed the influence of population structure and kinship on LD patterns in soybean. By the association mapping, we identified 181 markers associated with the ten traits evaluated in soybean. In addition, complex interactions between QTL and environments were verified. Differentially selected regions were identified between theBrazilian genotypes population and the population of materials from diverse origins, demonstrating that they underwent divergent selection processes.
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McSweeny, Andrew. "Genome Evolution Model (GEM): Design and Application." University of Toledo Health Science Campus / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=mco1290550446.
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Riep, Josette R. "Leveraging Artificial Intelligence to increase STEM Graduates Among Underrepresented Populations." University of Cincinnati / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1627663323829372.
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Al-Haddad, Luan Marie. "Neural network techniques for the identification and classification of marine phytoplankton from flow cytometric data." Thesis, University of South Wales, 2001. https://pure.southwales.ac.uk/en/studentthesis/neural-network-techniques-for-the-identification-and-classification-marine-phytoplankton-from-flow-cytometric-data(808c0828-1803-4e55-8ffd-6788ba36ad34).html.
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This thesis documents the research that has led to advances in the Artificial Neural Network (ANN) approach to analysing flow cytometric data from phytoplankton cells. The superiority of radial basis function networks (RBF) over multi-layer perception networks (MLP), for data of this nature, has been established, and analysis of 62 marine species of phytoplankton represents an advancement in the number of classes investigated. The complexity and abundance of heterogeneous phytoplankton populations, renders an original multi-class network redundant each time a novel species is encountered. To encompass the additional species, the original multiclass network requires complete retraining, involving long optimisation procedures to be carried out by ANN scientists. An alternative multiple network approach presented (and compared to the multi-class network), allows identification of the expanse of real world data sets and the easy addition of new species. The structure comprises a number of pre-trained single species networks as the front end to a combinatorial decision process for determining species identification. The simplicity of the architecture, and of the subsequent data produced by the technique, allows scientists unfamiliar with ANNs to dynamically alter the species of interest as required, without the need for complete re-training. Kohonens Self Organising Map (SOM), capable of discovering its own classification scheme, indicated areas of discrepancy between flow cytometric signatures of some species and their respective morphological groupings. In an attempt to improve identification to taxonomic group or genus level by supervised networks, class labels more reflective of flow cytometric signatures must be introduced. Methods for boundary recognition and cluster distinction in the output space of the SOM have been investigated, directed towards the possibility of an alternative flow cytometric structuring system. Performance of the alternative multiple network approach was comparable to that of the original multi-class network when identifying data from various environmental and laboratory culturing conditions. Improved generalisation can be achieved through employment of optical characteristics more representative of those found in nature.
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Pontin, David R. "Factors influencing the occurrence of stinging jellyfish (Physalia spp.) at New Zealand beaches." Lincoln University, 2009. http://hdl.handle.net/10182/1580.
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Individuals of the cnidarian genus Physalia are a common sight at New Zealand beaches and are the primary cause of jellyfish stings to beachgoers each year. The identity of the species and the environmental factors that determine its presence are unknown. Lack of knowledge of many marine species is not unusual, as pelagic invertebrates often lack detailed taxonomic descriptions as well as information about their dispersal mechanisms such that meaningful patterns of distribution and dispersal are almost impossible to determine. Molecular systematics has proven to be a powerful tool for species identification and for determining geographical distributions. However, other techniques are needed to indicate the causal mechanisms that may result in a particular species distribution. The aim of this study was to apply molecular techniques to the cnidarian genus Physalia to establish which species occur in coastal New Zealand, and to apply models to attempt to forecast its occurrence and infer some mechanisms of dispersal. Physalia specimens were collected from New Zealand, Australia and Hawaii and sequenced for Cytochrome c oxidase I (COI) and the Internal transcribed spacer 1 (ITS1). Three clans were found: a Pacific-wide clan, an Australasian clan and New Zealand endemic clan with a distribution confined to the Bay of Plenty and the East Coast of the North Island. Forecasting Physalia occurrence directly from presence data using artificial neural networks (ANN) proved unsuccessful and it was necessary to pre-process the presence data using a variable sliding window to reduce noise and improve accuracy. This modelling approach outperformed the time lagged based networks giving improved forecasts in both regions that were assessed. The ANN models were able to indicated significant trends in the data but would require more data at higher resolution to give more accurate forecasts of Physalia occurrence suitable for decision making on New Zealand beaches. To determine possible causal mechanisms of recorded occurrences and to identify possible origins of Physalia the presence and absence of Physalia on swimming beaches throughout the summer season was modelled using ANN and Naϊve Bayesian Classifier (NBC). Both models were trained on the same data consisting of oceanographic variables. The modelling carried out in this study detected two dynamic systems, which matched the distribution of the molecular clans. One system was centralised in the Bay of Plenty matching the New Zealand endemic clan. The other involved a dynamic system that encompassed four other regions on both coasts of the country that matched the distribution of the other clans. By combining the results it was possible to propose a framework for Physalia distribution including a mechanism that has driven clan divergence. Moreover, potential blooming areas that are notoriously hard to establish for jellyfish were hypothesised for further study and/or validation.
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Andersson, Mathias H. "Offshore wind farms - ecological effects of noise and habitat alteration on fish." Doctoral thesis, Stockholms universitet, Zoologiska institutionen, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-54049.
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There are large gaps in our understanding how fish populations are affected by the anthropogenic noise and the alteration of habitat caused by the construction and operation of offshore wind farms. These issues are of great importance as the construction of offshore wind farms will increase all over the world in the near future. This thesis studies these effects with a focus on fish. The wind turbine foundations function as artificial reefs and are colonized by invertebrates, algae and fish. The epibenthic assemblages are influenced by factors such as hydrographical parameters, time of submergence, distance to natural hard bottom, material and texture (PAPER I, II). Once an epibenthic assemblage has been developed, fish utilize it for different ecosystem services such as food, shelter, and spawning and nursery area. Benthic and semi-pelagic species show a stronger response to the introduced foundation than pelagic species, as it is the bottom habitat that has mainly been altered (PAPER I, II). Pelagic species could be positively affected by the increased food availability - but it takes time and the effect is local. Construction noise like pile driving creates high levels of sound pressure and acoustic particle motion in the water and seabed. This noise induces behavioural reactions in cod (Gadus morhua) and sole (Solea solea). These reactions could occur up to tens of kilometres distance from the source (PAPER III). During power production, the wind turbines generate a broadband noise with a few dominating tones (PAPER IV, V), which are detectable by sound pressure sensitive fish at a distance of several kilometres even though intense shipping occurs in the area. Motion sensitive species will only detect the turbine noise at around a ten meter distance. Sound levels are only high enough to possibly cause a behavioural reaction within meters from a turbine (PAPER IV, V).<br>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3, 4 and 5: Manuscripts.
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Lettink, Marieke, and n/a. "Adding to nature : can artificial retreats be used to monitor and restore lizard populations?" University of Otago. Department of Zoology, 2008. http://adt.otago.ac.nz./public/adt-NZDU20080715.091040.
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Artificial retreats are increasingly used to sample animal populations and in attempts to boost animal numbers in degraded habitats. Here, I test potential applications of artificial retreats for lizards inhabiting a coastal environment of high conservation value (Kaitorete Spit, New Zealand). I first conducted a pitfall-trapping survey examining the distribution and relative abundance of lizards in duneland, farmland and shrubland habitats, and tested the influence of trap placement on capture rates. Capture rates of the diurnal skinks Oligosoma maccanni (McCann�s skink) and O. nigriplantare polychroma (common skink) were highest in duneland and farmland, respectively, and were most sensitive to the distance separating traps from the nearest cover (the greater the distance, the lower the capture rate). Captures of O. lineoocellatum (spotted skink) and Hoplodactylus maculatus (common gecko) were rare.
Secondly, in separate chapters I test the utility of artificial retreats for monitoring: 1) a preference trial examining relative use of three types of artificial retreats by skinks (O. maccanni and O. n. polychroma) and geckos (H. maculatus); 2) a comparison of the effectiveness of artificial retreats relative to pitfall traps for detecting cryptic and primarily nocturnal geckos (H. maculatus) following translocation; and 3) capture-recapture estimation of population parameters (survival and abundance) of H. maculatus. I found that: 1) geckos strongly preferred retreats made of Onduline over corrugated iron and concrete tiles, whereas skinks exhibited no apparent preferences; 2) artificial retreats were more effective than pitfall traps for detecting geckos following translocation; and 3) monthly survival and recapture probabilities of geckos varied with age-class and over time. Estimated survival was unexpectedly low, possibly due to excessive trap spacing. I developed a new capture-recapture model specifically for population size estimation with data from artificial retreats, which gave estimates that were up to 50% greater than those predicted by conventional capture-recapture models. I caution that permanent placement of artificial retreats in long-term studies may be inappropriate for estimation of population parameters due to potential habitat-enhancement effects and/or altered predation risk.
Thirdly, I conducted a capture-recapture field experiment, using a replicated Before-After-Control-impact (BACI) design, to test the relative effects of habitat manipulation (artificial retreat addition) and partial predator removal (by fencing) on annual survival of duneland skink (O. maccanni) populations. Survival increased at sites with predator exclosures, but not at control sites or following the addition of artificial retreats, either alone or in combination with a predator exclosure. The magnitude of the increase in survival for the exclosure-only treatment was small, but sufficient to change the trajectory of an apparently stable population into an increasing one, suggesting that the population is limited by predators. Predator control, but not the addition of artificial retreats, is predicted to benefit O. maccanni.
To conclude, the Onduline design developed here appears to be particularly useful for sampling cryptic, terrestrial geckos; however, artificial retreats must be used appropriately to avoid bias arising from habitat-enhancing effects and/or altered predation risk. The restoration value of artificial retreats requires further testing on other species and in areas where natural retreat sites are limited.
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Hambelton, R. G. "The use of artificial substrates as a method of monitoring estuarine benthic invertebrate populations." Thesis, University of Salford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372155.
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Ladewig, Vanessa. "Der Einfluss von hormonell wirksamen Umweltchemikalien auf die Populationsökologie von Gammarus fossarum." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2004. http://nbn-resolving.de/urn:nbn:de:swb:14-1094121391765-54938.
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Bei zwei Fließgewässern (Lockwitzbach und Körsch) wurde ein Expositions- und Effektmonitoring an Probenahmestellen jeweils ober- und unterhalb des Einleiters eines kommunalen Klärwerks über einen Zeitraum von zwei Jahren durchgeführt. Gegenstand der vorliegenden Arbeit waren dabei die Untersuchungen zur Populationsstruktur und -dynamik von Gammarus fossarum (Amphipoda, Crustacea). Folgende Populationsvariablen wurden erfasst: Abundanz, Geschlechterverhältnis, Anteil von Juvenilen, Anteil brütender Weibchen, Fekundität, Körperlängen und Infektion mit Acanthocephalen. Erstmalig wurde Intersexualität bei G. fossarum festgestellt. Im Lockwitzbach war der Anteil an Intersexen bei den adulten Gammariden mit etwa 5 - 15 % höher als in der Körsch mit &lt; 1 %. Intersexualität wurde nicht durch die Einleiter induziert. Bei den Intersexen handelt es sich um funktionelle Weibchen. Wodurch dieses Phänomen ausgelöst wird und welche Bedeutung es für die Population hat, ist unbekannt. In den Freilanduntersuchungen wurden im Projekt Xehogamm (Umweltbundesamt Berlin, FKZ 299 65 221/05), in dessen Rahmen diese Dissertation entstand, verschiedene Umweltchemikalien im Bachwasser analysiert. Bei Vertebraten ist eine östrogene Wirksamkeit dieser Substanzen bekannt oder wird vermutet. In den Gammaridenpopulationen unterhalb der Klärwerkseinleiter waren wichtige populationsrelevante Variablen im Vergleich zu oberhalb verändert. An der unteren Probenahmestelle bei der Körsch war der Anteil der Juvenilen mit der kleinsten Körperlänge sowie der Anteil brütender Weibchen erniedrigt. Tendenziell traf dies auch für die untere Probenahmestelle beim Lockwitzbach zu. Bei der Körsch ist außerdem der frühere Beginn der herbstlichen Reproduktionspause und die geringere Körperlänge adulter Gammariden möglicherweise auf endokrine Umweltchemikalien im Wasser des Einleiters zurückzuführen. Von den nachgewiesenen Substanzen wurde eine Einzelsubstanz, Bisphenol A, für ein Fließrinnenexperiment ausgewählt. In künstlichen Fließrinnen im Gewächshaus wurde G. fossarum paarweise, in Gruppen sowie als größenstrukturierte Population in der Fließrinne selbst über 103 Tage exponiert, und verschiedene Populationsvariablen wurden erfasst. Die Nominalkonzentrationen von Bisphenol A in drei Fließrinnen betrugen 5, 50 und 500 µg/L. In den ersten drei aufeinanderfolgenden Bruten zeigte sich in der höchsten Bisphenol A-Konzentration die größte Brutgröße. Im weiteren Verlauf des Experiments übte Bisphenol A einen hemmenden Einfluss auf die Reproduktion der Gammariden aus. Basierend auf den Nominalkonzentrationen wurden folgende EC10-Werte berechnet: Anteil reproduzierender Weibchen für die 4. Brut (bei Gammaridenpaaren): 22 µg/L, Brutgröße der 4. Brut (bei Gammaridenpaaren): 11 µg/L, Anteil brütender Weibchen (Population): 212 µg/L und Anteil Juveniler (Population): 153 µg/L Bisphenol A. Die EC10-Werte basierend auf Effektivkonzentrationen für dieselben Endpunkte betragen: bei den Paaren 1,1 µg/L (reproduzierende Weibchen) und 0,5 µg/L (Brutgröße), in der Population 10 µg/L (Anteil brütender Weibchen und Anteil Juveniler). Im Fließrinnenexperiment wurde Bisphenol A zwar in höheren Konzentrationen als im Freiland vorhanden eingesetzt, die beobachteten Effekte weisen jedoch in dieselbe Richtung wie die Effekte im Freiland. Daher kann nicht ausgeschlossen werden, dass auch die Effekte im Freiland auf einer endokrinen Wirkung von Umweltchemikalien beruhen könnten. Zusätzlich wurde der Einfluss von Bisphenol A auf die Osmoregulation bei G. lacustris untersucht, wobei unterschiedliche Effekte auf die Natrium- und Calciumkonzentration, nicht jedoch auf die Osmolalität, in der Hämolymphe nachgewiesen wurden. Anlage: Rohdaten (3,87 MB)- Nutzung: Referat Informationsvermittlung der SLUB
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Vazquez, Rodriguez Juan Fernando. "Transformateurs multimodaux pour la reconnaissance des émotions." Electronic Thesis or Diss., Université Grenoble Alpes, 2023. http://www.theses.fr/2023GRALM057.
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La santé mentale et le bien-être émotionnel ont une influence significative sur la santé physique et sont particulièrement importants pour un viellissement en bonne santé. Les avancées continues dans le domaine des capteurs et de la microélectronique en général ont permis l’avènement de nouvelles technologies pouvant être déployées dans les maisons pour surveiller la santé et le bien-être des occupants. Ces technologies de captation peuvent être combinées aux avancées récentes sur l’apprentissage automatique pour proposer des services utiles pour vieillir en bonne santé. Dans ce cadre, un système de reconnaissance automatique d’émotions peut être un outil s’assurant du bien-être de personnes fragiles. Dès lors, il est intéressant de développer un système pouvant déduire des informations sur les émotions humaines à partir de modalités de captation multiples, et pouvant être entrainé sans requérir de larges jeux de données labellisées d’apprentissage.Cette thèse aborde le problème de la reconnaissance d’émotions à partir de différents types de signaux qu’un environnement intelligent peut capter, tels que des signaux visuels, audios, et physiologiques. Pour ce faire, nous développons différents modèles basés sur l’architecture extit{Transformer}, possédant des caractéristiques utiles à nos besoins comme la capacité à modéliser des dépendances longues et à sélectionner les parties importantes des signaux entrants. Nous proposons en premier lieu un modèle pour reconnaitre les émotions à partir de signaux physiologiques individuels. Nous proposons une technique de pré-apprentissage auto-supervisé utilisant des données physiologiques non-labellisées, qui améliore les performances du modèle. Cette approche est ensuite étendue pour exploiter la complémentarité de différents types de signaux physiologiques. Nous développons un modèle qui combine ces différents signaux physiologiques, et qui exploite également le pré-apprentissage auto-supervisé. Nous proposons une méthode de pré-apprentissage qui ne nécessite pas un jeu de données unique contenant tous les types de signaux utilisés, pouvant au contraire être pré-entrainé avec des jeux de données différents pour chaque type de signal.Pour tirer parti des différentes modalités qu’un environnement connecté peut offrir, nous proposons un modèle multimodal exploitant des signaux vidéos, audios, et physiologiques. Ces signaux étant de natures différentes, ils capturent des modes distincts d’expression des émotions, qui peuvent être complémentaires et qu’il est donc intéressant d’exploiter simultanément. Cependant, dans des situations d’usage réelles, il se peut que certaines de ces modalités soient manquantes. Notre modèle est suffisamment flexible pour continuer à fonctionner lorsqu’une modalité est manquante, mais sera moins performant. Nous proposons alors une stratégie d’apprentissage permettant de réduire ces baisses de performances lorsqu’une modalité est manquante.Les méthodes développées dans cette thèse sont évaluées sur plusieurs jeux de données. Les résultats obtenus montrent que nos approches de extit{Transformer} pré-entrainé sont performantes pour reconnaitre les émotions à partir de signaux physiologiques. Nos résultats mettent également en lumière les capacités de notre solution à aggréger différents signaux multimodaux, et à s’adapter à l’absence de l’un d’entre eux. Ces résultats montrent que les approches proposées sont adaptées pour reconnaitre les émotions à partir de multiples capteurs de l’environnement. Nos travaux ouvrent de nouvelles pistes de recherche sur l’utilisation des extit{Transformers} pour traiter les informations de capteurs d’environnements intelligents et sur la reconnaissance d’émotions robuste dans les cas où des modalités sont manquantes. Les résultats de ces travaux peuvent contribuer à améliorer l’attention apportée à la santé mentale des personnes fragiles<br>Mental health and emotional well-being have significant influence on physical health, and are especially important for healthy aging. Continued progress on sensors and microelectronics has provided a number of new technologies that can be deployed in homes and used to monitor health and well-being. These can be combined with recent advances in machine learning to provide services that enhance the physical and emotional well-being of individuals to promote healthy aging. In this context, an automatic emotion recognition system can provide a tool to help assure the emotional well-being of frail people. Therefore, it is desirable to develop a technology that can draw information about human emotions from multiple sensor modalities and can be trained without the need for large labeled training datasets.This thesis addresses the problem of emotion recognition using the different types of signals that a smart environment may provide, such as visual, audio, and physiological signals. To do this, we develop different models based on the Transformer architecture, which has useful characteristics such as their capacity to model long-range dependencies, as well as their capability to discern the relevant parts of the input. We first propose a model to recognize emotions from individual physiological signals. We propose a self-supervised pre-training technique that uses unlabeled physiological signals, showing that that pre-training technique helps the model to perform better. This approach is then extended to take advantage of the complementarity of information that may exist in different physiological signals. For this, we develop a model that combines different physiological signals and also uses self-supervised pre-training to improve its performance. We propose a method for pre-training that does not require a dataset with the complete set of target signals, but can rather, be trained on individual datasets from each target signal.To further take advantage of the different modalities that a smart environment may provide, we also propose a model that uses as inputs multimodal signals such as video, audio, and physiological signals. Since these signals are of a different nature, they cover different ways in which emotions are expressed, thus they should provide complementary information concerning emotions, and therefore it is appealing to use them together. However, in real-world scenarios, there might be cases where a modality is missing. Our model is flexible enough to continue working when a modality is missing, albeit with a reduction in its performance. To address this problem, we propose a training strategy that reduces the drop in performance when a modality is missing.The methods developed in this thesis are evaluated using several datasets, obtaining results that demonstrate the effectiveness of our approach to pre-train Transformers to recognize emotions from physiological signals. The results also show the efficacy of our Transformer-based solution to aggregate multimodal information, and to accommodate missing modalities. These results demonstrate the feasibility of the proposed approaches to recognizing emotions from multiple environmental sensors. This opens new avenues for deeper exploration of using Transformer-based approaches to process information from environmental sensors and allows the development of emotion recognition technologies robust to missing modalities. The results of this work can contribute to better care for the mental health of frail people
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Silva, Ivana Fernandes da 1986. "Desempenho de populações geográficas de Helicoverpa armigera (Hübner) (Lepidoptera : Noctuidae) em dietas naturais e artificial e caracterização por microssatélites /." Botucatu, 2017. http://hdl.handle.net/11449/150891.
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Orientador: Edson Luiz Lopes Baldin<br>Coorientador: Alexandre Specht<br>Banca: José Paulo Gonçalves Franco da Silva<br>Banca: Carlos Frederico Wilcken<br>Banca: Daniel Ricardo Sosa-Gomez<br>Banca: André Luiz Lourenção<br>Resumo: Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) possui ampla distribuição geográfica e é reponsável por perdas econômicas em várias culturas de importância agrícola ao redor do mundo. As lagartas apresentam grande plasticidade em termos de exigência nutricional e, devido à polifagia, se adaptam a diversos hospedeiros, com valores nutricionais variados, os quais podem afetar seu desenvolvimento biológico. Considerando a recente introdução do inseto no Brasil (2013), aliada à falta de consenso sobre a origem das populações a campo, dificuldades no estabelecimento de criações massais, bem como a necessidade de maior entendimento sobre sua interação com os hospedeiros em nosso país, este estudo teve como objetivos: disponibilizar uma dieta padronizada para criações de H. armigera em laboratório (25±2°C, 70±10% U.R. e 14h de fotofase), caracterizar molecularmente três populações, de São Paulo, Bahia e Distrito Federal, avaliar o desempenho biológico e o potencial biótico de indivíduos provenientes de diferentes populações em dieta artificial e investigar a performance de H. armigera em estruturas vegetativas e reprodutivas de algodão, milho e soja. As análises moleculares mostraram similaridade elevada entre indivíduos das três populações, indicando uma origem única para H. armigera no Brasil. O método de criação, bem como os índices nutricionais da dieta artificial oferecida se revelaram adequados para o inseto. A viabilidade média das fases larval e pré-pupal foi semelhan... (Resumo completo, clicar acesso eletrônico abaixo)<br>Abstract: Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) has a wide geographical distribution and contributes to economic losses in several crops of agricultural importance around the world. The larvae present great plasticity in terms of nutritional requirement and, due to polyphagia, they adapt to several hosts with varied nutritional values which may affect their biological development. Taking into account the recent introduction of these insects in Brazil (2013), along with the lack of consensus on the origin of their populations in the field, as well as the difficulties in establishing mass creations, and the need for greater understanding of their interaction with the hosts in our country, this study had as its objectives: to provide a standardized diet for laboratory H. armigera (25±2°C, 70±10% R.H., and 14h of phototophase); to molecularly characterize three populations from São Paulo (SP), Bahia (BA), and Distrito Federal (DF); to evaluate the biological performance and biotic potential of individuals from different populations on artificial diet; and to investigate the performance of H. armigera in vegetative and reproductive structures of cotton, corn and soybean. The molecular analyzes showed a high similarity between individuals of the three populations, which indicates a unique origin for H. armigera in Brazil. The breeding method, as well as the nutritional indexes of the artificial diet offered, was adequate for the insects. The mean viability of the larval and ... (Complete abstract click electronic access below)<br>Doutor
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Reed, Deborah A. "Spatial and temporal biogeochemical changes of groundwater associated with managed aquifer recharge in two different geographical areas." University of Western Australia. School of Biomedical, Biomolecular and Chemical Sciences, 2008. http://theses.library.uwa.edu.au/adt-WU2008.0074.
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[Truncated abstract] Managed Aquifer Recharge (MAR) is a technique that can be used to capture and store water in aquifers for later reuse. This method recycles water that would normally be lost or discarded to the environment. MAR has been observed to have the potential for improving the quality of recharged water through a combination of physical, chemical and biological processes. The aim of this study was to investigate the changes in groundwater microbial population structure during MAR and the major influences that drive these population changes. Biogeochemical MAR studies have the potential to assist in the improved prediction of the removal of contaminants such as nutrients, pathogens and trace organics from the recharged water. Biological clogging during recharge also has the potential to overwhelm an aquifers ability to process wastewater thus reducing the hydraulic conductivity of the aquifer. Therefore further research into the spatial and temporal biogeochemical processes that occur during MAR is required. The geochemical and microbial population dynamics of two contrasting MAR techniques were investigated at two different geographical locations (Perth, Western Australia and Adelaide, South Australia). These MAR sites contained aquifers of dissimilar properties that were recharged with wastewater that contrasted in water quality. The Perth MAR site received secondary treated effluent which continuously infiltrated the unsaturated zone into an unconfined aquifer aided by infiltration galleries. Reclaimed water was extracted from a well at distance from the infiltration gallery. ... Notably the background and recovered water was most dissimilar in microbial and chemical population structure to that described for the infiltration gallery and injection well. Microbial and chemical evidence suggested that the background and extraction well groundwater were unaffected by plume migration. These results suggested that extraction well groundwater was similar in quality to that of ambient groundwater. Significant geochemical and microbial changes of secondary treated effluent during infiltration and lateral movement through aquifer were implicated in addition to the forced hydraulic gradient created from extracting fives time the volume of infiltrating wastewater. This study demonstrated that microbial populations and the geochemical processes associated with MAR can be studied and compared. Multivariate statistical methodology greatly simplified a vast array of dynamic biogeochemical information that could be dissected for meaningful interpretation over distance and time. The study evaluated the major biogeochemical influences which resulted in microbial and geochemical changes where it was noted that microbial populations were more dynamic than geochemical variation over time. Additionally biogeochemical comparative analysis indicated that microbial populations could change in population structure before a shift in aquifer geochemistry was detected. It is anticipated that the results from this study will benefit further research into the biogeochemical processes involved in water quality changes (e.g. nutrient removal, pathogen decay and biodegradation of trace organics) as well as controlling biological clogging of MAR schemes.
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Blouet, Sylvain. "Vers une approche spatialisée de la planification spatiale marine : cas d’étude pour des populations d’invertébrés sessiles dans le Golfe du Lion." Electronic Thesis or Diss., Sorbonne université, 2023. http://www.theses.fr/2023SORUS292.
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La planification spatiale marine est un enjeu d’avenir pour la conservation des ressources marines, mais notre compréhension de l’agencement spatial des zones de conservation et des zones d'aménagement pour favoriser la persistance des populations n’est pas si claire. L’étude des échelles spatiales structurant la distribution des espèces et des processus influençant la dynamique et la persistance des populations marines est donc essentielle pour une approche spatialisée de l'organisation des espaces marins. Ce travail de thèse s’est donc organisé autour de deux objectifs : (i) appréhender les échelles locales et régionales structurant la distribution spatiale des invertébrés sessiles dans les habitats naturels et artificiels (partie 2 et partie 3) et (ii) évaluer comment l’intégration de la connectivité fonctionnelle associée à la dispersion larvaire dans un réseau hybride d’habitats naturels et d’habitats artificiels influencent les schémas prospectifs spatialisés d'extension de la conservation dans le golfe du Lion. Les approches choisies combinent des outils de modélisation et des inventaires à haute résolution d'invertébrés sessiles communs sur les habitats naturels et sur les récifs artificiels. La partie 2 examine la distribution spatiale régionale de 5 espèces de gorgones en utilisant un modèle de niche écologique, à partir de prédicteurs hydrologiques et géomorphologiques (courants de fond, température de surface, turbidité, profondeur, pente, rugosité, orientation des parois). La structuration spatiale de 4 des 5 espèces de gorgones peut s’expliquer par ces facteurs. Dans la partie 3, les effets de facteurs locaux (forme, profondeur et durée d'immersion) et régionaux (zone géographique) ont été évalués en examinant les assemblages de cinq espèces aux traits d'histoire de vie contrastés. Le positionnement géographique a été prévalent sur les facteurs locaux dans la colonisation des RA. L'approche multi spécifique réalisée dans les parties 2 et 3 a montré d’importances différentes du rôle de la dispersion et des facteurs abiotiques sur la structuration spatiale (locale et régionale) des espèces. Dans la partie 4, un schéma prospectif d'extension de la conservation a été simulé pour évaluer l'intégration de la connectivité fonctionnelle au sein du réseau de substrats rocheux naturels et avec l’ajout du réseau des récifs artificiels. Le réseau d'aires marines protégées est fortement modifié quand la connectivité fonctionnelle au sein de l’habitat naturel rocheux fragmenté est prise en compte. Le réseau des récifs artificiels, ajoutant des points relais dans le réseau des habitats naturels, modifie le schéma prospectif. Ces résultats soulignent l’importance d’intégrer la connectivité fonctionnelle dans la planification spatiale marine et le potentiel impact de l’installation ou du démantèlement de récifs artificiels<br>Marine spatial planning is a future issue for the conservation of marine resources, but our understanding of the spatial arrangement of conservation zones and management zones to promote the persistence of populations is not so clear. The study of spatial scales structuring the distribution of species and processes influencing the dynamics and persistence of marine populations is therefore essential for a spatialized approach to the organization of marine spaces. This thesis work is therefore organized around two objectives: (i) to understand the local and regional scales structuring the spatial distribution of sessile invertebrates in natural and artificial habitats (part 2 and part 3) and (ii) to evaluate how the he integration of functional connectivity associated with larval dispersal in a hybrid network of natural habitats and artificial habitats influences the spatialized prospective schemes of conservation extension in the Gulf of Lion. The chosen approaches combine modelling tools and high-resolution inventories of common sessile invertebrates on natural habitats and on artificial reefs. Part 2 examines the regional spatial distribution of 5 gorgonian species using an ecological niche model, based on hydrological and geomorphological predictors (bottom currents, surface temperature, turbidity, depth, slope, roughness, wall orientation). The spatial structuring of 4 of the 5 species of gorgonians can be explained by these factors. In part 3, the effects of local (shape, depth and duration of immersion) and regional (geographical area) factors were evaluated by examining the assemblages of five species with contrasting life history traits. Geographical positioning prevailed over local factors in AR colonization. The multi-specific approach carried out in parts 2 and 3 showed different importance of the role of dispersal and abiotic factors on the spatial structuring (local and regional) of species. In Part 4, a prospective conservation extension design was simulated to assess the integration of functional connectivity within the natural hard bottom and with the addition of the artificial reef network. The network of marine protected areas is strongly modified when the functional connectivity within the fragmented rocky natural habitat is taken into account. The network of artificial reefs, adding stepping stone in the network of natural habitats, modifies the prospective design. These results highlight the importance of integrating functional connectivity into marine spatial planning and the potential impact of installing or dismantling artificial reefs
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Bouteillé, Marie. "Control of shoot and root growth by water deficit in Arabidopsis thaliana : a parallel analysis using artificial and natural mapping populations." Thesis, Montpellier, SupAgro, 2011. http://www.theses.fr/2011NSAM0017/document.
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Le maintien de la croissance foliaire en situation de déficit hydrique résulte du maintien de l´absorption racinaire et de la production de biomasse au niveau foliaire. Pour optimiser les deux processus, la plante ajuste la croissance de ses organes, et la répartition de la biomasse produite, entre les différents organes (root/shoot ratio) ou au sein de chaque organe (surface foliaire spécifique, longueur racinaire spécifique). Les principaux objectifs de ce travail de thèse étaient (i) d´évaluer l´impact des modifications de répartition de biomasse sur le maintien de la croissance foliaire en situation de déficit hydrique, (ii) de relier la réponse de la croissance d´un génotype aux caractéristiques de son habitat d´origine, and (iii) d´identifier les régions du génome responsables de la variation des croissances foliaires et racinaires en situation de déficit hydrique. Différent types de populations d´Arabidopsis thaliana ont été utilisés, une population de lignées recombinantes, ainsi que différents groupes d´accessions collectées dans des environnements naturels contrastés. Une analyse des relations allométriques entre les variables foliaires et racinaires en conditions de culture optimales puis en situation de déficit hydrique a permis de mettre en évidence le rôle clé de la surface foliaire spécifique dans l´amélioration de la tolérance au déficit hydrique. Une caractérisation détaillée du climat des régions dans lesquelles les accessions avaient été collectées a permis de faire le lien entre la tolérance accrue de certains génotypes et la faible balance climatique dans laquelle ils évoluaient. Enfin, en utilisant ces génotypes, une analyse de génétique quantitative (combinant recherche de QTL et génétique d´association) a été menée. Les régions génomiques controllant les croissances foliaires et racinaires étaient très liées, en particulier en situation hydrique optimale, mais le calcul de variables utilisant la croissance de la plante comme cofacteur a permis d´identifier des régions spécifiques de la croissance racinaire, dont une a été confirmée en utilisant des lignées quasi isogéniques. En situation de contrainte hydrique, les déterminants génétiques des croissances foliaires et racinaires étaient moins liés, et plusieurs régions très fortement associées spécifiquement aux variations de croissance racinaire ou foliaire ont été détectées. Des régions associées au maintien de la croissance foliaire en situation de déficit hydrique ont pu être mises en évidence, et la précision des études de génétique d´association a permis de réveler la présence de gènes d´intéret dans ces régions<br>Growth maintenance under water deficit mainly results from the maintenance of water uptake at the root level,and assimilates production by leaves. To optimize both processes, plant need to adjust organ growth and biomassallocation patterns between roots and shoots (root/shoot ratio), but also within the organs, through specific leaf areaand specific root length variations. The main objectives of this study were (i) to evaluate the impact of growth andbiomass allocation patterns modifications on growth maintenance under drought conditions, (ii) to rely the genotypicresponses to water deficit conditions and the climatic features of the natural environment in which they evolved, and(iii) to identify the key genetic regions responsible for shoot and root growth variation in response to water deficitconditions. We used different sets of genotypes, a population of recombinant inbred lines, and different sets ofaccessions of Arabidopsis thaliana, collected in a wide range of environments. An analysis of the allometricrelationships between shoot and root growth related variables under both well watered and water deficit conditionsallowed to highlight the importance of specific leaf area plasticity to maintain plant growth under water deficit. Adetailed climatic characterization of the natural habitats of the accessions studied, combined to the evaluation ofgrowth response to water deficit in these accessions allowed connecting low climatic water balance to better toleranceto water deficit conditions in specific regions, suggesting that this climatic feature could have shaped the evolution ofgenotypes in certain regions. Finally, using these two sets of genotypes, joint linkage and linkage disequilibriumanalysis were performed on growth related traits under well watered and water deficit conditions. Some genetic regionsinvolved in the control of root and shoot related traits were strongly coupled, especially in well watered experiments,but we managed to identify root specific regions using calculated variables that takes global plant growth as a cofactor.Under water deficit, the regions controlling root and shoot growth were less associated, and very strong QTL weredetected, specifically associated to one or the other part. Genomic regions associated to growth response to waterdeficit were also detected, and the accuracy of association mapping enabled to identify target genes that could be playa role in growth maintenance under drought
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Tacuatiá, Luana Olinda. "Les aspects de la variabilité génétique et cytogénétique, et de la biologie reproductive chez Sisyrinchium micranthum Cav. (Iridaceae) dans le sud du Brésil." Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00922984.
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Sisyrinchium micranthum Cav. is an herbaceous plant, one of the rare species of the genus which is described as annual. In Brazil, its distribution occurs throughout the states of Rio Grande do Sul (RS), Santa Catarina (SC), Paraná (PR), São Paulo (SP), and Rio de Janeiro (RJ). The species has a wide morphological variability reported in several studies, and different combinations of morphological features can be observed in the wild. Based on these combinations that characterize various plant profiles, three morphological types have been described as CI, CII and CIII. Sisyrinchium micranthum has three ploidy levels described in the literature whose basic number is x = 8, 2n = 2x = 16, 2n = 4x = 32, and 2n = 6x = 48. To contribute to the knowledge on the taxonomy, reproduction and evolution of the species, this study investigated genetic and cytogenetic characteristics of S. micranthum, as well as aspects of reproductive biology. To study the population genetic structure of S. micranthum in southern Brazil, firstly, nine microsatellite markers were isolated using an enriched genomic library, and characterized in a diploid population. Later, from the analysis of genetic variability with seven markers for 583 plants of 14 sampled sites in the states of RS, SC and PR, populations with individuals of different ploidy levels were observed. An autopolyploid origin was presumed for these polyploids. The gene and allelic diversities were rather similar for most of the accessions. The inbreeding coefficient over all loci showed that S. micranthum exhibited an average excess of heterozygotes (negative inbreeding coefficient value), but the FIS values of individual populations ranged from -0.273 to 0.454. The heterozygote excess could be expected since autopolyploids present polysomic inheritance, which contributes substantially for a high heterozygosity. In addition, the populations were highly structured. The results from the cytogenetic analyses, demonstrated that the variability of S. micranthum is also present in terms of genome organization. Regarding S. micranthum and related species S. laxum Otto ex Sims and S. rosulatum E.P. Bicknell, it was verified that the 18S-26S rDNA varies in number of loci, with a notable reduction of the same in polyploids in relation to diploids, while 5S locus showed a proportional increase in the number of signals as increased ploidy level. The data on genome size (Cx) for the three species studied showed a genome downsizing from diploids to polyploids, and also a small inter and intraspecific variation with respect to the C-value. In terms of reproductive biology, selfing and outcrossing were recorded for the species. Furthermore, crossing between different morphological categories of S. micranthum are compatible as resulted in the formation of fruits. Likewise, the data suggest that S. micranthum and S. laxum do not present complete reproductive isolation. The genetic variability of S. micranthum demonstrated in this study in terms of genetic divergence between populations and variation in rDNA loci number possibly reflect the complex relationship between polyploidy and reproductive aspects of the species.
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CUNHA, KELLY de P. "Aplicação de mapas auto-organizáveis na classificação de aberrações cromossômicas utilizando imagens de cromossomos humanos submetidos à radiação ionizante." reponame:Repositório Institucional do IPEN, 2015. http://repositorio.ipen.br:8080/xmlui/handle/123456789/23828.
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Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2015-07-23T11:16:06Z
No. of bitstreams: 0<br>Made available in DSpace on 2015-07-23T11:16:06Z (GMT). No. of bitstreams: 0<br>Dissertação (Mestrado em Tecnologia Nuclear)<br>IPEN/D<br>Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Enz, Carole Enz Carole Andrea. "Population dynamics of whitefish (Coregonus suidteri Fatio) in artificially oxygenated Lake Hallwil, with special emphasis on larval mortality and sustainable management /." [S.l.] : [s.n.], 2000. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=13706.
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Weber, Tessmann Elisane. "IMPACT OF A WARMED ENVIRONMENT, SPIKE MORPHOLOGY AND GENOTYPE ON FHB LEVELS IN A SOFT RED WINTER WHEAT MAPPING POPULATION." UKnowledge, 2019. https://uknowledge.uky.edu/pss_etds/116.
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Fusarium head blight (FHB) is a serious disease of wheat (Triticum aestivum) and other small grains; disease severity is affected by temperature and rainfall. This research comprised three studies: an artificially warmed experiment during 2016-2017, a morphology study and an FHB resistance screening study in 2015-2016, using approximately 250 wheat cultivars and breeding lines from programs in the eastern US. The location was the University of Kentucky Spindletop Research Farm in Lexington, KY. Higher levels of Fusarium damaged kernels and the toxin deoxynivalenol (DON) were observed in the warmed treatment compared to the control, and plant development was accelerated. In the FHB resistance screen, significant (p < 0.05) genotype differences for all traits were observed. A GWAS identified 16 SNPs associated with resistance and susceptibility, ranging from -2.14 to 4.01%. Three DON-associated SNPs reduced toxin levels by 3.2, 2.1, and 1.5 ppm. In the morphology study, negative correlations were observed among morphological and disease traits. Small effect SNPs were identified for all morphological traits, which might be useful in genomic selection; traits like spike length, spikelet number and inclination could be used in phenotyping. Response to warming indicates that existing resistance sources may be less effective in a warming climate.
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Garcia, Flavien. "Dynamiques écologiques au sein de lacs artificiels : des communautés de poissons au fonctionnement de l'écosystème." Electronic Thesis or Diss., Université de Toulouse (2023-....), 2024. http://www.theses.fr/2024TLSEP143.
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Les écosystèmes d'eau douce figurent parmi les plus menacés, confrontés à de nombreuses perturbations telles que les invasions biologiques et la pollution. En réponse à ces pressions, leur biodiversité et leurs fonctions peuvent subir de forts changements au fil du temps. Ces perturbations ont entraîné des déclins marqués de la biodiversité, notamment chez les poissons, essentiels au fonctionnement des écosystèmes. Cette thèse vise à explorer les moteurs des dynamiques écologiques – des communautés de poissons au fonctionnement des écosystèmes – dans les lacs d'eau douce. Pour étudier ces dynamiques, nous avons utilisé un suivi sur dix ans dans des lacs artificiels, qui peuvent connaître des processus écologiques similaires à ceux des écosystèmes naturels, mais à un rythme plus rapide en raison de leur artificialité et de l'impact humain constant. Plus précisément, nous avons : (i) identifié le vecteur probable de colonisation initiale des poissons via une approche multidisciplinaire, (ii) analysé les changements dans la composition des communautés et leurs moteurs en quantifiant les variations de contributions des lacs et espèces à la bêta-diversité, (iii) utilisé un cadre de trajectoire écologique pour examiner la dynamique des structures trophiques, et (iv) utilisé la télédétection pour étudier la dynamique temporelle de la production primaire des lacs et son lien avec la structure des réseaux trophiques – reconstruite via un cadre de modélisation bayésien. Nos résultats soutiennent la zoochorie aviaire comme vecteur initial de colonisation. L'eutrophisation et les invasions biologiques se sont révélées être des moteurs clés des changements dans les communautés, devenant de plus en plus dominées par des espèces non indigènes à mesure que les lacs maturent. Ces changements ont été liés à des modifications de la structure trophique, avec des chaînes trophiques plus longues et une plus grande redondance trophique. Enfin, nous avons constaté que la structure des réseaux trophiques – influencée par la morphologie et la maturité des lacs – semblait liée à la dynamique de la production primaire, les lacs avec des réseaux trophiques plus complexes présentant une production primaire plus stable. Les résultats de cette thèse suggèrent des dynamiques écologiques interconnectées. Bien que la dynamique des communautés soit initialement façonnée par la colonisation naturelle, l'eutrophisation et les invasions biologiques d'origine humaine entraînent un remplacement d’espèces, remodelant ainsi les structures trophiques des communautés. Ensuite, la structure des réseaux trophiques influence les fluctuations des fonctions écosystémiques. Cette thèse constitue une base essentielle pour comprendre ces dynamiques et ouvre de nouvelles perspectives pour explorer leurs interconnexions, notamment concernant les fonctions écosystémiques, cruciales pour le maintien de la biodiversité et des services écosystémiques<br>Freshwater ecosystems rank among the most threatened, facing a wide range of disturbances such as biological invasion and pollution. As these ecosystems respond to such pressures, both their biodiversity and functions can undergo substantial changes over time. These threats have driven significant biodiversity declines, especially in fish, which are essential for ecosystem functioning. This thesis aims to explore the drivers of ecological dynamics – from fish communities to ecosystem functioning – in freshwater lakes. To investigate such dynamics we used a decade-long survey of artificial lakes, which can experience ecological processes similar to those in natural ecosystems but at a faster rate due to their artificial nature and ongoing human impact. Specifically, we: (i) identified the most likely vector for initial fish colonization using a multidisciplinary approach, (ii) analyzed changes in fish community composition and their drivers by quantifying changes in lake and species contributions to beta-diversity, (iii) applied an ecological trajectory tool to examine fish trophic structure dynamics, and (iv) used remote sensing to study the temporal dynamics of lake primary production and its link to food web structure – reconstructed via a Bayesian modeling framework. Our results strongly support avian-zoochory as an initial colonization pathway. Eutrophication and biological invasions emerged as key drivers of fish community changes, with fish communities becoming increasingly dominated by non-native species as lakes mature. These compositional changes were linked to shifts in trophic structure, mainly towards longer food chains and greater trophic redundancy. Finally, we found that food web structure – driven by lake morphology and maturity – seemed related to primary production dynamics, with lakes that have more complex food webs exhibiting more stable primary production. The findings throughout the thesis suggest interconnected ecological dynamics. While community dynamics are initially shaped by natural colonization, human-induced eutrophication and biological invasions drive species turnover, reshaping community trophic structures. Then, food web structures influence fluctuations in ecosystem function. This research lays a key foundation for understanding ecological dynamics and opens new avenues for exploring their interconnections; particularly regarding ecosystem functions, which are critical to maintaining biodiversity and ecosystem services
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Harrington, Rhidian. "The effects of artificial watering points on the distribution and abundance of avifauna in an arid and semi-arid mallee environment." Connect to this title online, 2002. http://repository.unimelb.edu.au/10187/2874.
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The role of artificial watering points in the avifaunal dynamics of the semi-arid mallee woodlands of southeast Australia was examined. Species richness and abundance were monitored throughout the year at different distances from water to determine how birds were distributed around water points and how this changed in relation to environmental factors such as climate. Vegetation attributes were also measured to determine which factors explained patterns in the avifauna with distance from water, and also to allow a description of the vegetation in relation to the water points. Water points were monitored throughout the year to determine which species were utilising them, under which environmental circumstances and for what purposes. Knowledge of the water utilisation behaviour of individual bird species allowed some explanation of their distribution patterns, as well as an ability to predict the likely effects of water point closure on those bird species. The closure of two water points during the study allowed an assessment of the immediate effects of water point closure on avifauna (For complete abstract open document)
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Pastor, Jérémy. "Rôle des enrochements côtiers artificiels dans la connectivité des populations, cas du sar commun (Diplodus sargus, Linné, 1758) en Méditerranée nord-occidentale." Phd thesis, Université de Perpignan, 2008. http://tel.archives-ouvertes.fr/tel-00344703.
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La destruction d'une partie des habitats est souvent la cause principale de leur fragmentation. Or, depuis les années 1960-1970, l'anthropisation du littoral du golfe du Lion a engendré la création d'habitats fragmentés, non pas par une destruction, mais bien par un apport nouveau via l'installation massive d'enrochements côtiers artificiels. Cette étude a eu pour but principal de comprendre le rôle de ces structures en comparaison à des zones naturelles (lagunes, zone rocheuse) dans le maintien des populations de poissons de la côte rocheuse située plus au sud. Le sar commun, poisson caractéristique des zones rocheuses, a été utilisé comme modèle. Des comptages d'adultes et de juvéniles en plongée subaquatique, des marquages directs mais aussi l'utilisation de la microanalyse chimique des otolithes ont été utilisés afin de répondre à ces interrogations. Les aménagements littoraux jouent un rôle de nourricerie non négligeable. Selon les années, les densités de juvéniles sont de 30 à 109 fois supérieures à celles observées sur les habitats naturels, que ce soit sur la côte rocheuse ou dans la lagune. La présence de seulement deux groupes principaux de géniteurs sur la côte catalane française pourrait expliquer de telles différences. Un des deux alimenterait les enrochements côtiers artificiels, il serait situé au cap Leucate. Le second, dans la réserve de Cerbère-Banyuls exporterait des juvéniles vers la côte espagnole suivant un courant dominant nord-sud. De plus, la lagune aurait perdu son rôle de nourricerie au profit des aménagements littoraux. Nos résultats montrent aussi qu'il existe une connectivité lors de la phase adulte entre ces structures côtières et les zones rocheuses naturelles. Elle a lieu principalement au printemps et en automne. 20 % des sars ayant fait leur installation sur les aménagements littoraux les quittent pour la côte rocheuse. Sur cette côte un tiers des sars sont issus d'une installation sur des habitats artificiels de la côte sableuse. Cette étude souligne le rôle majeur que peuvent avoir ces habitats artificiels dans le maintien, voire l'extension des populations de sars communs au niveau de la côte catalane, mais aussi de l'ensemble du golfe du Lion. La fragmentation de l'habitat est dans ce cas positive. Elle pourrait être à l'origine de l'apparition de nouvelles espèces sur la côte du Languedoc-Roussillon comme le sar tambour, Diplodus cervinus et le denti, Dentex dentex
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Zhu, Bin. "Impact des barrages sur la génétique des populations d'esturgeon chinois (Acipenser sinensis) : contribution du repeuplement des juvéniles à la diversité des populations naturelles." Toulouse 3, 2004. http://www.theses.fr/2004TOU30069.
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D'un point de vue historique, l'echinois (Acipenser sinensis) était autrefois abondant, ayant une large distribution en Chine, notamment dans les rivières Jaune, Pearl et YangTze, ainsi qu'à différentes localités de la mer de Chine. Cependant, durant ces dernières décennies, l'espèce a connu une forte baisse de ses effectifs et est désormais classée sur la liste rouge (IUCN) en Chine. La rivière YangTze pourrait ainsi héberger les dernières populations d'esturgeon chinois. Cependant, depuis la mise en place du barrage Gezhouba en 1981, la migration de cette espèce vers la zone de frayère dans la partie amont se trouve ainsi bloquée. L'espèce est ainsi en danger de disparition, d'autant plus que s'ajoutent des effets croissants de la pollution, de la pression de pêche et des pertes des zones de frayère. Des besoins de restauration ont été reconnus et des mesures de conservation de l'espèce ont été mises en place. Ainsi, depuis 1983, la pêche commerciale est strictement interdite, et depuis 1984, des larves et des juvéniles d'esturgeon ont été réintroduits artificiellement dans la rivière YangTze. Pour évaluer les impacts du recrutement des individus issus de l'introduction artificielle sur la population naturelle, nous avons utilisé des marqueurs microsatellitaires (pour identifier les variabilités génétiques) et la carte auto-organisatrice (SOM, algorithme à apprentissage non supervisé du réseau de neurones) pour classer des résultats obtenus. Dans un premier temps, les loci de microsatellites ont été obtenus à partir de la librairie génomique partielle des poissons et des amorces de microsatellites développées pour les autres espèces d'esturgeon. Un total de 10 loci microsatellitaires sont ainsi amplifiés pour l'esturgeon chinois, mais 6 uniquement ont été utilisés en raison du fort taux de polymorphisme et pour faciliter la reproductibilité et le génotypage. Dans un second temps, la structure et la diversité génétique de l'esturgeon chinois ont été examinées utilisant les loci microsatellitaires de 60 géniteurs sauvages capturés durant 3 années consécutives (1999 à 2001). Les résultats révèlent que l'esturgeon chinois présente un faible niveau de variation génétique à l'intérieur de la population et la réduction de son abondance n'entraîne pas de variation génétique au sein de l'espèce. . .
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Westlake, Douglas M. "The impact of artificial propagation on Pacific salmon stocks and fisheries and an application of captive broodstock rearing technology to rebuild severely depressed populations of Thompson River coho." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0017/MQ54576.pdf.
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Bouchoucha, Marc. "Les zones portuaires peuvent-elles servir de nourriceries alternatives pour les poissons marins côtiers ? : cas des sars en Méditerranée Nord-occidentale." Thesis, Perpignan, 2017. http://www.theses.fr/2017PERP0046/document.
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Au cours de leur cycle de vie, la plupart des espèces de poissons marins côtiers passent par des nourriceries littorales dont la qualité influence largement le succès du recrutement et donc le maintien de l’abondance de leurs populations. Or, la construction de ports entrain irrémédiablement une perte de fonction pour les habitats côtiers impactés. Dans ce contexte,l’objectif général de cette thèse était de voir si les zones portuaires peuvent malgré tout servir de nourriceries alternatives pour les poissons marins côtiers. Pour cela, les abondances des juvéniles de quatre espèces de sars, du genre Diplodus, ont d’abord été suivies dans cinq ports méditerranéens. Ceci a permis de montrer que ces espèces côtières peuvent s’installer et grandir avec succès dans les ports. La complexification de la structure 3D de l’habitat augmente sensiblement les abondances de juvéniles. Dans un second temps, la croissance, la condition et les niveaux de contamination desjuvéniles de deux espèces de sars (D. sargus et D. vulgaris) ont été comparés entre différents ports et habitats naturels de la rade de Toulon. Ceci a montré que la croissance et la condition des juvéniles peut être équivalente dans certains ports et dans les zones naturelles adjacentes, avec des niveaux de contamination faibles, même dans les zones les plus polluées. Enfin, la composition multi- élémentaire des otolithes des juvéniles de D. sargus et D. vulgaris a été comparée entre trois ports et deux zones naturelles de la rade de Toulon. Aucun élément chimique lié aux activités portuaires n’aété retrouvé en plus forte concentration dans les otolithes des juvéniles issus des ports. Il n’existe donc pas une signature unique caractéristique de l’ensemble des ports. La composition chimique des otolithes peut néanmoins être utilisée pour étudier la contribution relative des ports aux stocks d’adultes à condition de caractériser la signature de l’ensemble des habitats juvéniles potentiels. L’ensemble des résultats acquis indiquent que les ports peuvent être utilisés comme nourriceries alternatives par plusieurs espèces de poissons marins côtiers. Les projets d’ingénierie écologiquevisant à augmenter la complexité structurale des habitats portuaires sont des pistes intéressantes pour maintenir la biodiversité côtières et les stocks de poissons<br>During their life cycle, most of the marine coastal fish species use nursery grounds which quality influence their recruitment and then the conservation of their populations. However, the construction of ports impair irremediably fish nursery function of the coastal areas impacted. The ultimate aim of the PhD research was to assess if ports could provide suitable alternative nursery habitats for coastal fish species. Firstly, abundances of the juveniles of four Diplodus species were surveyed in five marinas located along the French Mediterranean coast. This showed that coastal fishes can successfully settle and grow inside these artificialized coastal areas. Moreover, increasing the complexity of port habitats can considerably enhance their suitability for juveniles, especially at the youngest stages. Secondly, body condition, growth rate and metal contamination in the juveniles of two Diplodus species (D. sargus and D. vulgaris) were compared between different ports and natural areas in the Bay of Toulon. Juvenile growth and condition can be equivalent between fish collected from ports and from adjacent natural areas. Contamination levels in fish were low, even in highly polluted areas. Finally, otolith composition in the juveniles of D. sargus and D. vulgaris was investigated in three ports and two natural areas in the Bay of Toulon. None of the port related had systematically higher concentrations in otoliths from Diplodus juveniles collected in ports. Therefore, otolith microchemistry cannot provide a unique and reliable fingerprint discriminating ports and natural areas. Nevertheless, otolith microchemistry could provide an effective natural tag to determine the contribution of ports to adult stocks provided that a library of all potential juvenile habitat fingerprints is established. All these results confirm that ports can be used as alternative nursery habitats by marine coastal fishes. Ecological engineering projects aiming at increasing structural complexity of port habitats seem promising for biodiversity and fish stock conservation
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Schmidt, Jens. "Wirkung von Umweltchemikalien auf Gammarus fossarum - Populationsexperimente und individuenbasiertes Reproduktionsmodell." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2004. http://nbn-resolving.de/urn:nbn:de:swb:14-1090321181000-52636.
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Das Schutzziel in der Ökotoxikologie ist die Population. Untersuchungen zur Wirkung von subletalen Konzentrationen einer Umweltchemikalie auf Populationsebene, zum Beispiel mit künstlichen Fließgewässersystemen (Mikrokosmen) können aussagekräftigere Beiträge zur ökotoxikologischen Bewertung einer Umweltchemikalie liefern. Außerdem können bei solchen Untersuchungen mögliche indirekte Effekte erfaßt werden. Über die Reaktion von Fließgewässer-Biozönosen gegenüber Umweltchemikalien ist relativ wenig bekannt. Die überwiegende Zahl der Untersuchungen zur Abschätzung des Gefährdungspotentials von Umweltchemikalien wurde mit Testsystemen für Lebensgemeinschaften in stehenden Gewässern untersucht. Die Übertragbarkeit der Ergebnisse dieser Tests auf Fließgewässer-Lebensgemeinschaften ist meist nicht gegeben. Daher ist es notwendig Testsysteme zu etablieren, mit denen die Wirkung von Umweltchemikalien auf Fließgewässer-Lebensgemeinschaften untersucht werden kann. In einem Gewächshaus wurden fünf Fließrinnen etabliert, mit denen die physikalisch-chemischen Bedingungen in einem Bach simuliert werden können. Im Gegensatz zu Untersuchungen einer komplexen Lebensgemeinschaft mit hoher Variabilität, wie sie sich beispielsweise durch das Einbringen von natürlichem Sediment aus Fließgewässern einstellt, wurde in diesen Experimenten die Wirkung von Chemikalien auf eine einfache Lebensgemeinschaft untersucht. Die Lebensgemeinschaft in den Fließrinnen bestand deshalb aus wenigen, ausgewählten Arten. Untersucht wurden die Konzentrationen 0,6, 6, 60 und 600 µg/l (Terbutryn) und 0,05, 0,5, 5 und 50 µg/l (Fenoxycarb). Gegenstand der vorliegenden Arbeit waren die Untersuchungen mit Gammarus fossarum. In einem akuten Toxizitätstest wurde die LC50 von Terbutryn für adulte und juvenile Gammariden ermittelt. In den Fließrinnenexperimenten mit Terbutryn und Fenoxycarb wurden populationsrelevante Parameter der Gammaridenpopulationen untersucht. Ob und in welchem Umfang sich Effekte, die mit den Standardtests gemessen wurden, auf bestimmte ökotoxikologische Endpunkte der Population auswirken, kann nicht immer unmittelbar abgeleitet werden. Eine Möglichkeit wäre die aufwendige Durchführung von Populationsexperimenten mit einfachen oder komplexeren Modellökosystemen über eine lange Zeit. Eine andere Möglichkeit ist die Nutzung mathematischer Modelle zur Beschreibung der Populationsdynamik. Das begleitend zu den Untersuchungen entwickelte individuenbasierte Reproduktionsmodell GamMod bildet die Populationsdynamik einer abgeschlossenen Population von Gammarus fossarum in künstlichen Fließgewässersystemen ab. Es wird die Struktur und Dynamik des realen Systems (Populationsdynamik) unter Einbeziehung der Kenntnisse des Reproduktionszyklus modelliert. Modellszenarien sollen Aussagen über den Einfluß der Änderung einer Variablen bezüglich der Populationsdynamik liefern.
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Schmidt, Jens. "Wirkung von Umweltchemikalien auf Gammarus fossarum - Populationsexperimente und individuenbasiertes Reproduktionsmodell." Doctoral thesis, Technische Universität Dresden, 2003. https://tud.qucosa.de/id/qucosa%3A24352.
Full textAbstract:
Das Schutzziel in der Ökotoxikologie ist die Population. Untersuchungen zur Wirkung von subletalen Konzentrationen einer Umweltchemikalie auf Populationsebene, zum Beispiel mit künstlichen Fließgewässersystemen (Mikrokosmen) können aussagekräftigere Beiträge zur ökotoxikologischen Bewertung einer Umweltchemikalie liefern. Außerdem können bei solchen Untersuchungen mögliche indirekte Effekte erfaßt werden. Über die Reaktion von Fließgewässer-Biozönosen gegenüber Umweltchemikalien ist relativ wenig bekannt. Die überwiegende Zahl der Untersuchungen zur Abschätzung des Gefährdungspotentials von Umweltchemikalien wurde mit Testsystemen für Lebensgemeinschaften in stehenden Gewässern untersucht. Die Übertragbarkeit der Ergebnisse dieser Tests auf Fließgewässer-Lebensgemeinschaften ist meist nicht gegeben. Daher ist es notwendig Testsysteme zu etablieren, mit denen die Wirkung von Umweltchemikalien auf Fließgewässer-Lebensgemeinschaften untersucht werden kann. In einem Gewächshaus wurden fünf Fließrinnen etabliert, mit denen die physikalisch-chemischen Bedingungen in einem Bach simuliert werden können. Im Gegensatz zu Untersuchungen einer komplexen Lebensgemeinschaft mit hoher Variabilität, wie sie sich beispielsweise durch das Einbringen von natürlichem Sediment aus Fließgewässern einstellt, wurde in diesen Experimenten die Wirkung von Chemikalien auf eine einfache Lebensgemeinschaft untersucht. Die Lebensgemeinschaft in den Fließrinnen bestand deshalb aus wenigen, ausgewählten Arten. Untersucht wurden die Konzentrationen 0,6, 6, 60 und 600 µg/l (Terbutryn) und 0,05, 0,5, 5 und 50 µg/l (Fenoxycarb). Gegenstand der vorliegenden Arbeit waren die Untersuchungen mit Gammarus fossarum. In einem akuten Toxizitätstest wurde die LC50 von Terbutryn für adulte und juvenile Gammariden ermittelt. In den Fließrinnenexperimenten mit Terbutryn und Fenoxycarb wurden populationsrelevante Parameter der Gammaridenpopulationen untersucht. Ob und in welchem Umfang sich Effekte, die mit den Standardtests gemessen wurden, auf bestimmte ökotoxikologische Endpunkte der Population auswirken, kann nicht immer unmittelbar abgeleitet werden. Eine Möglichkeit wäre die aufwendige Durchführung von Populationsexperimenten mit einfachen oder komplexeren Modellökosystemen über eine lange Zeit. Eine andere Möglichkeit ist die Nutzung mathematischer Modelle zur Beschreibung der Populationsdynamik. Das begleitend zu den Untersuchungen entwickelte individuenbasierte Reproduktionsmodell GamMod bildet die Populationsdynamik einer abgeschlossenen Population von Gammarus fossarum in künstlichen Fließgewässersystemen ab. Es wird die Struktur und Dynamik des realen Systems (Populationsdynamik) unter Einbeziehung der Kenntnisse des Reproduktionszyklus modelliert. Modellszenarien sollen Aussagen über den Einfluß der Änderung einer Variablen bezüglich der Populationsdynamik liefern.
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Mezgueldi, Hamid El. "L'adaptation aux sols salés de l'espèce rudérale "Dittrichia viscosa" W. Greuter : recherche d'une différenciation de populations sur un gradient de salinité de 60 mètres." Montpellier 2, 1992. http://www.theses.fr/1992MON20215.
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Ce travail a pour but d'etudier l'eventualite d'une differenciation ecotypique dans un jeune peuplement de dittrichia viscosa, age de moins de 15 ans et etale le long d'un transect, d'environ 60 metres, presentant un gradient de salinite. L'etude de terrain a permis de delimiter quatre sites, chacun comprenant quelques individus du peuplement de dittrichia viscosa, d'analyser les sols et nappes phreatiques sous-jacentes et d'etudier l'impact du gradient sur la composition floristique, la taille et la survie des plantes le long du transect. Les comparaisons du comportement des plantes de dittrichia viscosa du transect, quelles soient issues graines et cultivees sur terre ou issues de clones et cultivees en hydroponie, ont montre que les plantes de la zone la plus salee du transect (site 1) different fonctionnellement de celles de la zone non salee (site 4). Ces differences nutritionnelles se sont montrees transmissibles des parents a leur descendance et persistantes d'une experimentation a l'autre. La comparaison des plantes des sites extremes, en hydroponie simulant des conditions de secheresse et d'anoxie n'a pas montre de differences entre ces deux groupes de plantes. Neanmoins, dittrichia viscosa s'est montree comme une espece resistante aux conditions de secheresse et d'anoxie
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Dorat, Rémi. "Répartition spatiale en théorie des jeux évolutionnaires." Phd thesis, Université des Sciences et Technologie de Lille - Lille I, 2009. http://tel.archives-ouvertes.fr/tel-00839387.
Full textAbstract:
La thése poursuit les travaux de la théorie des Jeux évolutionnaires Cette théorie est un cadre de modehsation de la dynamique des populations dans lequel les interactions entre agents sont modélisées par des dilemmes classiques de la théorie des Jeux. Les agents interagissent avec leurs pairs et les meilleurs comportements se diffusent. les moins performants tendent à disparaître. Les modèles spécifiés mettent notamment en évidence des conditions sur les rapports inter-individuels qui permettent de faire émerger des équilibres coopératifs. En supposant que chaque agent a des relations non plus avec tous les agents de la population mais seulement avec un sous-ensemble des agents de la population et toujours avec les mêmes, on augmente considérablement le nombre des dynamiques possibles. Cette démarche fait apparaître un réseau des interactions,.soit un graphe. La contrainte spatiale s'avère une condition favorable au maintien des comportements coopératifs et de la biodiversité des comportements. L'analyse formelle de la convergence n'est généralement plus possible et les modèles sont étudiés par simulation. La these poursuit l'étude de l'impact de la répartition spatiale. Elle introduit un nouveau modèle de répartition spatiale où des communautés d'agents sont en réseau et non plus des agents. Ce modèle permet de mettre en évidence de nouvelles formes d'attracteurs coopératifs et de nouvelles conditions au maintien de la biodiversité. La thèse montre aussi la possibilité de convergence de marchés vers des équilibres non concurrentiels et de maintien de comportements coopératifs, des comportements de cartel.
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Aurelle, Didier. "Contacts secondaires naturels et artificiels chez la truite commune (Salmo trutta, L. ) des Pyrénées occidentales françqises : utilisation de marqueurs microsatellites pour la distinction de taxons faiblement différenciés." Montpellier 2, 1999. http://www.theses.fr/1999MON20087.
Full textAbstract:
L'objectif de cette these est l'etude des interactions genetiques entre differentes formes de truite commune (salmo trutta, l. ) dans les pyrenees occidentales francaises. Dans cette region, deux formes de truites sauvages sont presentes et cohabitent avec une forme domestique. Une etude de genetique des populations a ete realisee a l'aide de 6 locus microsatellites. En dehors des parametres genetiques classiques, l'interpretation a fait appel a des techniques d'analyses multivariees (analyse factorielle des correspondances) ou d'assignations individuelles (reseaux de neurones artificiels, methodes probabilistes). Par ailleurs, la variabilite de la region de controle de l'adn mitochondrial a ete etudiee par pcr-sscp puis sequencage. Ces marqueurs ont permis de mettre en evidence une forte structuration genetique entre populations et entre groupes de populations. Des deficits en heterozygotes importants ont ete observes dans certaines populations. Par ailleurs, l'impact des repeuplements a ete estime dans cette zone et indique une situation contrastee, avec des populations tres introgressees et d'autres peu influencees par les repeuplements. L'efficacite et l'interet de ces pratiques sont discutes. Par ailleurs, la sequence des differents haplotypes mitochondriaux a permis de les situer par rapport aux grands types europeens pour une etude phylogeographique. La plupart faisaient partie du groupe atlantique et n'avaient pas ete identifies auparavant. Des hypotheses concernant l'evolution et l'origine des populations de cette region sont proposees.
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Dorat, Rémi. "Répartition spatiale en théorie des jeux évolutionnaires." Electronic Thesis or Diss., Lille 1, 2009. http://www.theses.fr/2009LIL10040.
Full textAbstract:
La thése poursuit les travaux de la théorie des Jeux évolutionnaires Cette théorie est un cadre de modehsation de la dynamique des populations dans lequel les interactions entre agents sont modélisées par des dilemmes classiques de la théorie des Jeux. Les agents interagissent avec leurs pairs et les meilleurs comportements se diffusent. les moins performants tendent à disparaître. Les modèles spécifiés mettent notamment en évidence des conditions sur les rapports inter-individuels qui permettent de faire émerger des équilibres coopératifs. En supposant que chaque agent a des relations non plus avec tous les agents de la population mais seulement avec un sous-ensemble des agents de la population et toujours avec les mêmes, on augmente considérablement le nombre des dynamiques possibles. Cette démarche fait apparaître un réseau des interactions,.soit un graphe. La contrainte spatiale s'avère une condition favorable au maintien des comportements coopératifs et de la biodiversité des comportements. L'analyse formelle de la convergence n'est généralement plus possible et les modèles sont étudiés par simulation. La these poursuit l'étude de l'impact de la répartition spatiale. Elle introduit un nouveau modèle de répartition spatiale où des communautés d'agents sont en réseau et non plus des agents. Ce modèle permet de mettre en évidence de nouvelles formes d'attracteurs coopératifs et de nouvelles conditions au maintien de la biodiversité. La thèse montre aussi la possibilité de convergence de marchés vers des équilibres non concurrentiels et de maintien de comportements coopératifs, des comportements de cartel<br>The thesis continues the work of Evolutionary Game Theory. This theory is a framework for modeling the dynamics of populations interactions betwcen agents are modeled by the classic dilemmas from Game Theory. The agents interaet with their peers. Best behaviors spread. less suecessful ones tend to disappear. Evolutionary Game Theory prondes conditions upon which cooperative behaviors can survive and cooperative equilibriums can appear. Assuming that each agent does not interact with all the others but only with a fixed group of neighbors greatly increases the number of possible dynamics. The relations between agents form a social network. Limitation of contacts between agents favors cooperative equilibrium and biodiversity. Nevertheless, formal approach to the models is no longer possible and they are studied through massive computer simulations. The thesis continues the study of the impact of social networks. lt introduces networks of communities, a new model where commnnities are networked rather than agents. This model exhibits new forms of eooperative convergence and new conditions to persistent biodiversity. The thesis also shows the possibility of convergence of markets towards non-competitive equilibriums and the survival of behaviors collectively able to reach cartel equilibrium, a particular form of cooperative equilibrium