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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
391

Spatiotemporal Dynamics of Multi-Scale Habitat Selection in an Invasive Generalist

Paolini, Kelsey Elizabeth 04 May 2018 (has links)
Spatiotemporal dynamics of resource availability can produce markedly different patterns of landscape utilization which necessitates studying habitat selection across biologically relevant extents. Feral pigs (Sus scrofa) are a prolifically expanding, generalist species and researchers have yet to understand fundamental drivers of space use in agricultural landscapes within the United States. To study multi-scale habitat selection patterns, I deployed 13 GPS collars on feral pigs within the Mississippi Alluvial Valley. I estimated resource selection using mixed-effects models to determine how feral pigs responded to changes in forage availability and incorporated those results with autocorrelated kernel density home range estimates. My results indicated season-specific habitat functional responses to changes in agricultural phenology and illustrated the interdependencies of landscape composition, hierarchical habitat selection, and habitat functional responses. These results indicate fundamental drivers of feral pig spatial distributions in an agricultural landscape which I used to predict habitat use to direct feral pig management.
392

Personnel Selection in the Digital Age: A Review of Validity and Applicant Reactions, and Future Research Challenges

Woods, S.A., Ahmed, S., Nikolaou, I., Costa, Ana-Cristina, Anderson, Neil 14 October 2019 (has links)
Yes / We present a targeted review of recent developments and advances in digital selection procedures (DSPs) with particular attention to advances in internet-based techniques. By reviewing the emergence of DSPs in selection research and practice, we highlight five main categories of methods (online applications, online psychometric testing, digital interviews, gamified assessment and social media). We discuss the evidence base for each of these DSP groups, focusing on construct and criterion validity, and applicant reactions to their use in organizations. Based on the findings of our review, we present a critique of the evidence base for DSPs in industrial, work and organizational psychology and set out an agenda for advancing research. We identify pressing gaps in our understanding of DSPs, and ten key questions to be answered. Given that DSPs are likely to depart further from traditional nondigital selection procedures in the future, a theme in this agenda is the need to establish a distinct and specific literature on DSPs, and to do so at a pace that reflects the speed of the underlying technological advancement. In concluding, we, therefore, issue a call to action for selection researchers in work and organizational psychology to commence a new and rigorous multidisciplinary programme of scientific study of DSPs.
393

Avaliação da eficiência do teste precoce no melhoramento genético de soja / Evaluation of early generation testing effectiveness in soybean breeding

Carvalho, Agnaldo Donizete Ferreira de 10 April 2008 (has links)
O teste em gerações precoces no melhoramento genético de plantas consiste em identificar e selecionar progênies promissoras em gerações iniciais de endogamia, tais como F2 ou F3, e com isso concentrar tempo e recursos somente em populações com potencial para gerar linhas puras superiores. Considerando a ocorrência de relatos conflitantes, este trabalho teve como objetivo avaliar a eficiência do teste precoce no melhoramento genético de soja, utilizando uma população derivada de um cruzamento biparental entre as linhagens 14 e 38, contrastantes para produção de grãos, e selecionadas do cruzamento entre os genitores PI-123439 e PI-239235. Os tratamentos consistiram de uma amostra de 100 progênies de cada tipo: F2:3, F3:4 e F4:5, que foram avaliadas em experimentos em látice 10 x 10 no ano agrícola 2005/6 na área experimental do Departamento de Genética da ESALQ/USP, em Piracicaba, SP. Os experimentos foram avaliados novamente no ano agrícola 2006/7, em dois locais: Piracicaba, SP e Anhumas, SP, utilizando, para isso, os bulks oriundos dos experimentos do ano anterior, isto é, progênies F2:4, F3:5 e F4:6,. A parcela experimental foi constituída de uma linha de 2 m de comprimento, espaçada de 0,5 m, contendo 35 plantas por parcela após o desbaste. Foram avaliados os seguintes caracteres: altura das plantas no florescimento (AF), dias para florescimento (DF), altura das plantas na maturação (AM), dias para maturação (DM) e produção de grãos por parcela (PG). Devido à baixa taxa de germinação das sementes nos experimentos derivados de plantas F3 (F3:4 e F3:5) e, consequentemente à baixa precisão experimental, estes foram excluídos do estudo. Com base nos resultados dos experimentos de 2005/6 foram estimadas as variâncias genéticas e fenotípicas, os coeficientes de herdabilidades e as respostas esperadas com seleção, supondo diferentes intensidades (20%, 30%, 40% e 50%). Com base nos resultados das avaliações de 2006/7 foram obtidas as respostas observadas com seleção, que possibilitaram avaliar a eficiência do teste precoce nas diferentes intensidades de seleção. Observou-se uma boa correspondência entre as respostas preditas e observadas somente para as progênies F4:5, fato este já esperado, considerando o alto grau de heterozigose nas progênies F2:3. Os resultados gerais indicaram que a seleção em geração tão precoces como F2:4 pode ser efetuada, desde que sejam utilizadas intensidades moderados de seleção, da ordem de 40%. / Early generation testing in plant breeding consists of selecting progenies in early generations of selfing such as in F2 or F3, in order to save time and resources. The objective of this work was to assess the early generation testing effectiveness in soybean breeding programs. The base population consisted of a two way cross between inbred lines 14 and 38, derived from the cross between PI-123439 and PI-239235 parents. Entries consisted of a sample of 100 progenies of each generation: F2:3, F3:4 e F4:5, evaluated in lattice 10 x 10 designs in the 2005/6 growing season at Department of Genetics (ESALQ/USP) in Piracicaba, SP. In the 2006/7 growing season new experimental evaluations were performed, using the same experimental designs, in two locations: Piracicaba, SP, and Anhumas, SP, where the entries consisted of bulks derived from 2005/6 entries, i.e., F2:4, F3:5 and F4:6 progenies. Plots consisted of single 2-meter-long rows spaced 0.5 meter apart, with 37 plants after thinning in all experiments. The following traits were evaluated: plant height at flowering (AF), days to flowering (DF), plant height at maturity (AM), days to maturity (DM), and grain yield (PG). Due to the low germination rate and, consequently, the low experimental precision, experiments of F3 derived lines (F3:4 and F3:5) were eliminated. Estimates of genetics variances, heritabilities and expected response to selection, considering four selection intensities (20%, 30%, 40% e 50%) were obtained from 2005/6 evaluations. The observed responses to selection were obtained from the 2006/7 experiments, in order to evaluate the effectiveness of early selection. A good correspondence between estimated and observed responses to selection were observed only for experiments based on F4 derived lines, which is expected, considering the higher degree of heterozigosity of the progenies in as early generations as in F2. General results has shown that selection based in early generation as in F2 can be performed, using moderate intensities of selection, such as 40%.
394

The evolutionary implications of polyandry in house mice (Mus domesticus)

Firman, Renee C. January 2008 (has links)
[Truncated abstract] Despite the costs associated with mating, females of many taxa solicit multiple mates during a single reproductive event (polyandry). Polyandry is clearly adaptive when females gain direct benefits from males at mating. However, polyandry has also been shown to increase female fitness in the absence of direct benefits. Thus, a number of genetic benefit hypotheses have been developed to account for the origin of this behaviour. Although not mutually exclusive, a distinction lays between genetic benefits that propose defense against reproductive failure (nonadditive genetic effects), and those that propose benefits from intrinsic sire effects (additive genetic effects). Nonadditive genetic benefits of polyandry have been documented in a number of species; by soliciting multiple mates females can avoid inbreeding and other forms of incompatibility between parental genotypes. Polyandry may also increase female reproductive success when genetically superior males have greater success in sperm competition, and produce better quality offspring. An inevitable consequence of polyandry is that sperm from rival males will overlap in the female reproductive tract and compete to fertilise the ova. The outcome of sperm competition is typically determined by bias in sperm use by the females, interactions between parental genotypes, and ejaculate characteristics that provide a fertilisation advantage. Thus, sperm competition is recognised as a persuasive force in the evolution of male reproductive traits. Comparative analyses across species, and competitive mating trials within species have suggested that sperm competition can influence the evolution of testis size and sperm production, and both sperm form and sperm function. ... After six generations of selection I observed phenotypic divergence in litter size - litter size increased in the polyandrous lines but not in the monandrous lines. This result was not attributable to inbreeding depression, or environmental/maternal effects associated with mating regime. Genetic benefits associated with polyandry could account for this result if increased litter size were attributable to increased embryo survival. However, males from the polyandrous lineages were subject to sperm competition, and evolved ejaculates with more sperm, suggesting that evolutionary increases in litter size may in part be due to improved male fertility. Finally, Chapter Five is an investigation of the natural variation in levels of polyandry in the wild, and the potential for sperm competition to drive macroevolutionary changes in male reproductive traits among geographically isolated island populations of house mice. I sampled seven island populations of house mice along the coast of Western Australia and, by genotyping pregnant females and their offspring, determined the frequency of multiply sired litters within each population. I applied the frequency of multiple paternity as an index of the risk of sperm competition, and looked for selective responses in testis size and ejaculate traits. I found that the risk of sperm competition predicted testis size across the seven island populations. However, variation in sperm traits was not explained by the risk of sperm competition. I discuss these results in relation to sperm competition theory, and extrinsic factors that influence ejaculate quality.
395

Evolution of Spur Length in a Moth-pollinated Orchid

Boberg, Elin January 2010 (has links)
There is considerable evidence that pollinator shifts can explain many differences in flower morphology between closely related plant species, but the extent to which pollinator shifts can explain the maintenance of among-population variation in floral traits within species is poorly known. In this thesis, I combined comparative and experimental approaches to examine the evolution of floral traits in the moth-pollinated orchid Platanthera bifolia. More specifically, I investigated (1) the relationship between flower and pollinator morphology, (2) phenotypic selection on morphology and phenology in populations in contrasting environments, (3) components of prezygotic reproductive isolation among divergent populations, and (4) the adaptive and functional significance of two correlated floral traits. A study of Scandinavian of P. bifolia populations revealed that spur length was positively correlated with proboscis length of local pollinators, which suggests that variation in spur length reflects adaptive evolution in response to geographically variable pollinator-mediated selection. A phenotypic selection study on Öland, SE Sweden, suggested that disruptive selection on spur length contributes to the maintenance of a bimodal distribution of spur length in mixed habitats, but provided very limited evidence of divergent selection on plant morphology and flowering phenology in grassland and woodland habitats. Field experiments revealed strong reproductive isolation between divergent populations on Öland, due to differences in spatial distribution, flowering phenology, and pollinators, and among-population incompatibility. The results suggest that prezygotic reproductive isolation contributes to the maintenance of population differentiation in floral traits in P. bifolia. A field manipulation experiment demonstrated that spur length but not perianth size affects pollination success and seed production. This suggests that among-population differentiation in perianth size may be the result of a genetic correlation with spur length. Taken together, the results of this thesis suggest that pollinator-mediated selection can shape the evolution of intraspecific floral variation.
396

Optimal randomized and non-randomized procedures for multinomial selection problems

Tollefson, Eric Sander 20 March 2012 (has links)
Multinomial selection problem procedures are ranking and selection techniques that aim to select the best (most probable) alternative based upon a sequence of multinomial observations. The classical formulation of the procedure design problem is to find a decision rule for terminating sampling. The decision rule should minimize the expected number of observations taken while achieving a specified indifference zone requirement on the prior probability of making a correct selection when the alternative configurations are in a particular subset of the probability space called the preference zone. We study the constrained version of the design problem in which there is a given maximum number of allowed observations. Numerous procedures have been proposed over the past 50 years, all of them suboptimal. In this thesis, we find via linear programming the optimal selection procedure for any given probability configuration. The optimal procedure turns out to be necessarily randomized in many cases. We also find via mixed integer programming the optimal non-randomized procedure. We demonstrate the performance of the methodology on a number of examples. We then reformulate the mathematical programs to make them more efficient to implement, thereby significantly expanding the range of computationally feasible problems. We prove that there exists an optimal policy which has at most one randomized decision point and we develop a procedure for finding such a policy. We also extend our formulation to replicate existing procedures. Next, we show that there is very little difference between the relative performances of the optimal randomized and non-randomized procedures. Additionally, we compare existing procedures using the optimal procedure as a benchmark, and produce updated tables for a number of those procedures. Then, we develop a methodology that guarantees the optimal randomized and non-randomized procedures for a broad class of variable observation cost functions -- the first of its kind. We examine procedure performance under a variety of cost functions, demonstrating that incorrect assumptions regarding marginal observation costs may lead to increased total costs. Finally, we investigate and challenge key assumptions concerning the indifference zone parameter and the conditional probability of correct selection, revealing some interesting implications.
397

Personalo atrankos sistemos įtaka žmogiškųjų išteklių valdymui smulkiame ir vidutiniame versle / Personnel selection influence to human resources management in small and medium business

Šafranauskaitė, Kristina 08 September 2009 (has links)
Darbe analizuojama personalo atrankos sistemos įtaka žmoniškųjų išteklių valdymui smulkiame ir vidutiniame versle. Pirmoje dalyje supažindinama su įvairių autorių požiūriais į žmogiškųjų išteklių sampratą, reikšmę bei vaidmenį įmonės valdyme. Analizuojama atrankos proceso vieta bei įtaka įmonės veiklos bei žmogiškųjų išteklių valdymo efektyvumui. Svarbu paminėti, kad personalo atranka turi įtakos įmonės konkurencingumui, reputacijai, užima svarbią vietą žmogiškųjų išteklių valdyme, tuo pačiu veikdama ir kitas sistemos dalis. Personalo atrankos proceso metu atskleidžiamos organizacijos vertybės bei kultūra, kurios formuoja organizacijos įvaizdį, o tvirta įmonės kultūra rodo, kad firmoje tinkamai vadovaujama ir investuojama į žmogiškąjį turtą. Be to, atsirenkant tinkamiausius tam tikrai darbo vietai naujus darbuotojus, galima pasiekti didelio veiklos efektyvumo. Darbe pateikiamos personalo atrankos proceso etapų problemos bei nagrinėjama jų įtaka. Kadangi pirmas personalo parinkimo žingsnis- personalo poreikio planavimas, tad pirmiausia ir supažindinama su personalo poreikio planavimo svarba. Toliau analizuojamos verbavimo, atrankos metodų taikymo metu iškylančios problemos ir jų sprendimo būdai. Antroje darbo dalyje pateikti atlikto tyrimo, kuriuo siekiama išsiaiškinti vadovų ir darbuotojų požiūrį į atrankos procesą, rezultatai. Tyrime iškeliamos hipotezės: smulkiose ir vidutinėse įmonėse per maža dėmesio skiriama strateginei personalo atrankai. Neįvertinamos atrankos metu... [toliau žr. visą tekstą] / This study includes analysis of personnel selection process influence to human resources management in small and medium business. First part has identified the importance of personnel selection in the performance of the business. It is important to understand that organizational values can be shown over all selection process and values of an organization can influence candidate’s job choice. Therefore selection systems should leave applicants with the perception that they have been treated fairly, and one important and easy way to accomplish this is to treat people fairly. Additionally, effective personnel selection enhances a strategic advantage for their organization, may improve image and "reputation capital" for those firms. So, the hiring process is critical to a company's success - the right employee helps the company to reach its objectives but the wrong employee will cost the company a great deal in time, money and energy. The research about personnel selection procedures in Lithuania chosen for analytical part of this study. The research object – the personnel selection process in small and medium business. There are analysed attitudes of employees and employers about problems in personnel selection, most popular selection methods, recruitment sources, about the importance and value of selection in organizations. According to the results of the survey, the most popular way for employees selection is recommendation of acquaintances, friends. The survey found that the... [to full text]
398

Risikomessung mit dem Conditional Value-at-Risk : Implikationen für das Entscheidungsverhalten /

Hanisch, Jendrik. January 2006 (has links)
Universiẗat, Diss.--Jena, 2004.
399

Partnerwahl- und Heiratsmuster in modernen Gesellschaften : der Einfluss des Bildungssystems /

Timm, Andreas. January 2004 (has links)
Zugl.: Bremen, Universiẗat, Diss., 2003.
400

The dynamical systems theory of natural selection

Bentley, Michael January 2016 (has links)
Darwin's (1859) theory of evolution by natural selection accounts for the adaptations of organisms, but, as Fisher (1930) famously said, 'natural selection is not evolution.' Evolutionary theory has two major components: i) natural selection, which involves the underlying dynamics of populations; and ii) adaptive evolutionary change, which involves the optimisation of phenotypes for fitness maximisation. Many of the traditional theoretical frameworks in evolutionary theory have focussed on studying optimisation processes that generate biological adaptations. In recent years, however, a number of evolutionary theorists have turned to using frameworks such as the 'replicator dynamics' or 'eco-evolutionary dynamics', to explore the dynamics of natural selection. There has, however, been little attempt to explore how these dynamical systems frameworks relate to more traditional frameworks in evolutionary theory or how they incorporate the principles that embody the process of evolution by natural selection, namely, phenotypic variation, differential reproductive success, and heritability. In this thesis, I use these principles to provide the formal foundations of a general framework - a mathematical synthesis - in which the future state of an evolutionary system can be predicted from its present state; what I will call a 'dynamical systems theory of natural selection.' Given the state of an existing biological system, and a set of assumptions about how individuals within the system interact, the job of the dynamical systems theory of natural selection is no less than to predict the future in its entirety.

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