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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.
11

Análise filogenética de Mydinae (Insecta, Diptera, Mydidae) com base em caracteres morfológicos e moleculares / Phylogenetic analysis of Mydinae (Insecta, Diptera, Mydidae) based on morphological and molecular characters

Julia Calhau Almeida 04 April 2013 (has links)
A subfamília Mydinae (Insecta, Diptera, Mydidae) ocorre somente nas Américas e é composta por 12 gêneros e 84 espécies, sendo a grande maioria das espécies de Mydidae pertencentes a essa subfamília. Mydinae é atualmente dividida em quatro tribos: Dolichogastrini, Mydini, Phylomydini e Messiasiini. A monofilia da subfamília, assim como de suas tribos e gêneros, ainda não havia sido testada por análises filogenéticas, o que justifica os objetivos deste trabalho, que são: 1)testar a monofilia da subfamília Mydinae; 2)verificar o relacionamento filogenético dos Mydinae com outras subfamílias de Mydidae; 3)testar a monofilia das tribos, subtribos e gêneros de Mydinae, assim como a monofilia dos grupos de espécies do gênero Mydas; 4)propor uma nova classificação para a subfamília, baseada nos resultados filogenéticos. A partir de dados da morfologia externa de adultos, e também de sequência de DNA do gene COI, dois métodos de análise foram empregados: análises de parcimônia, com pesagem igual dos caracteres, e análises probabilísticas bayesianas. Para cada um dos métodos, foram analisados os dados morfológicos e moleculares separadamente, e também em conjunto. A monofilia de Mydinae, conforme delimitada na classificação vigente, não é corroborada no presente trabalho, em nenhuma das análises. Nas duas análises com dados morfológicos, e na análise bayesiana com dados morfológicos e moleculares, foi recuperado um clado formado por todos os Mydinae (exceto Messiasia wilcoxi) + Paramydas (\'Apiophorinae\'). Dentre as tribos de Mydinae, não foi recuperada a monifilia de Messiassiini e Mydini. Já os gêneros Ceriomydas, Stratiomydas, Phyllomydas e Protomydas foram reconhecidos como mofiléticos. Já os gêneros Baliomydas, Gauromydas, Messiasia e Mydas, não formaram grupos monofiléticos em nenhuma das análises. Neste trabalho, puderam ser testadas as monofilias de quatro dos cinco grupos de espécies de Mydas: clavatus, fulvifrons, interruptus e xanthopterus, sendo o grupo hardyi monotípico. Apenas o grupo interruptus foi recuperado como monofilético, embora seja reconhecido aqui que os caracteres de coloração tradicionalmente utilizados para a separação dos grupos não foram utilizados. A subfamília Apiophorinae, com amostragem de quatro espécies, não foi recuperada como monofilética, com o gênero Eumydas agrupando-se aos Rhopaliinae. A classificação de Mydinae é aqui revisada, porém devido à incerteza razoável quanto ao relacionamento entre alguns grupos, alguns táxons da classificação tradicional foram mantidos, apesar de não serem monofiléticos / The Mydinae (Insecta, Diptera, Mydidae) occur only in the Americas and comprise 12 genera and 84 species, of which the vast majority of mydids occurring in Brazil belonging to this subfamily. Mydinae is currently divided into four tribes: Dolichogastrini, Messiasiini, Mydini and Phylomydini. The monophyly of the subfamily, as well as the monophyly of their tribes and genera, had not yet been tested by phylogenetic analysis. Concerning this fact, the objectives of this work are: 1) test the monophyly of the subfamily Mydinae, 2) check the phylogenetic relationship between Mydinae and other subfamilies of Mydidae, 3) test the monophyly of the tribes, subtribes and genera of Mydinae, as well as the monophyly of the species-groups of the genus Mydas; 4) propose a new classification of the subfamily based on phylogenetic results. The data from the external morphology of adults, and also DNA sequence of the COI gene, two methods of analysis were used: parsimony analysis with equal weighting of characters, and Bayesian probabilistic analysis. For each method, morphological and molecular data were analyzed separately and also in combination. The monophyly of Mydinae, as defined in the current classification, is not borne out in the present study. In both analyzes with morphological data, and Bayesian analysis with morphological and molecular data, a clade formed by all Mydinae (except Messiasia wilcoxi) + Paramydas (\'Apiophorinae\') was recovered. Among the tribes of Mydinae, the monophylies of Messiassiini and Mydini were not recovered. The genera Ceriomydas, Stratiomydas, Phyllomydas and Protomydas are recognized as natural groups. In the other hand, the genera Baliomydas, Gauromydas, Messiasia and Mydas did not form monophyletic groups in any of the conducted analyzes. Concerning the Mydas species-groups, only the interruptus group was recovered as monophyletic, although it is recognized here that color based characters traditionally used for separating the groups were not used in the present work. The subfamily Apiophorinae, with four species sampled, was not recovered as monophyletic, with genus Eumydas grouping to Rhopaliinae. The classification of Mydinae is reviewed here, but due to reasonable uncertainty as to the relationships between some groups, some taxa of the traditional classification were kept, although not recognized as monophyletic
12

Experiment and bias: the case of parsimony in comparative cognition

Meketa, Irina 22 January 2016 (has links)
Comparative cognition is the interdisciplinary field of animal cognition and behavior studies, which includes comparative psychology and branches of ethology, biology, and neuroscience. My dissertation shows that the quasi-epistemic value of parsimony plays a problematic role in the experimental setting of comparative cognition. More specifically, I argue that an idiosyncratic interpretation of the statistical hypothesis-testing method, known as the Neyman-Pearson Method (NPM), embeds an Occamist parsimony preference into experimental methodology in comparative cognition, which results in an underattribution bias, or a bias in favor of allegedly simple cognitive ontologies. I trace this parsimony preference to the content of the null hypothesis within the NPM, and defend a strategy for modifying the NPM to guard against the underattribution bias. I recommend adopting an evidence-driven strategy for choosing the null hypothesis. Further, I suggest a role for non-empirical values, such as ethical concerns, in the weighting of Type I and Type II error-rates. I contend that statistical models are deeply embedded in experimental practice and are not value-free. These models provide an often overlooked door through which values, both epistemic and non-epistemic, can enter scientific research. Since statistical models generally, and the NPM in particular, play a role in a wide variety of scientific disciplines, this dissertation can also be seen as a case study illustrating the importance of attending to the choice a particular statistical model. This conclusion suggests that various philosophical investigations of scientific practice - from inquiry into the nature of scientific evidence to analysis of the role of values in science - would be greatly enriched by increased attention to experimental methodology, including the choice and interpretation of statistical models.
13

Simplicity in science

Schulz, Daniel Benjamin 01 May 2012 (has links)
This dissertation investigates the possibility of justifying simplicity principles in science. The labor of these projects is organized into three chapters. The first chapter introduces some of the key authors and issues in the history of simplicity in science. This chapter also gives a detailed discussion of the work of the 19th century physicists Le Verrier and Newcomb who played a crucial role in setting the stage for Einstein's theory of relativity. These examples are used to illustrate points in the following chapters. However, they play a specific role in the first chapter to show serious problems with a view defended by an important contemporary author, Richard Swinburne, that one version of the principle of parsimony contributes to the probability that scientific theories will be true. The second chapter elucidates the problems involved in specifying and measuring the simplicity of scientific hypotheses and theories. When simplicity criteria are employed in a scientific methodology, we find that simplicity judgments of one kind are always traded-off with simplicity judgments of another kind. We also find that the scientific project involves a delicate balancing of several aims. This analysis renders a valuable result: that some dogmas, in particular, the dogma that principles of parsimony are the final court of appeal in scientific theory selection must be jettisoned. I also find that it is misguided to ask the question of whether or not simplicity of some clearly specified kind is related to the truth. In point of fact, the legitimate questions about the justification of specific simplicity judgments in science are much more complex and nuanced than this. This becomes clear when it is seen exactly how different simplicity criteria are related to one another and to the various desiderata of science. The third chapter investigates which argument forms may be available to justify simplicity principles in science. In some cases it is nonsense to ask the question of how simplicity is related to the truth. However, we can investigate the forms of various arguments that may be given to justify methodological principles involving simplicity criteria. The results from the second chapter are employed in two ways. First, methodological principles stand in a tight-knit set of interrelations, so our analysis of justificatory argument forms must incorporate the complexity of these relations. Second, simplicity is extremely heterogeneous and since no conceptual reduction of all of the various simplicity criteria is possible, justificatory arguments must deal with clusters of interrelated principles. This result may have certain advantages and other disadvantages for inductive, transcendental, or inference to the best explanation approaches to the justification of simplicity. My analysis shows what will and what will not work for these possible approaches to the question of justification and shows what some of the systematic and metaphilosophical commitments would have to be were philosophers to pursue this project.
14

Phylogeny of Five Taxa in the Felsenstein and Farris Zones

Lam, Eric Trung 18 March 2021 (has links)
Mathematical conditions which showed where parsimony was not consistent for four taxa were first introduced by Felsenstein in 1978. This was subsequently labelled the "Felsenstein zone". Following Felsenstein's findings, 'frequentists' conjectured that for five taxa there would also be a region in parameter space where parsimony is not consistent. In response, 'cladists' claimed that parsimony was consistent in a different region of parameter space, which is called the "Farris zone". However, no analytical description of the region in which this consistency occurs has been made. Furthermore, no mathematical extensions of this Felsenstein theory to five taxa or more has been made. The same is true for the Farris zone. In this thesis, we give a complete account for the Felsenstein zone and Farris zone for four and five taxa and interpret these in terms of the shape of the phylogenetic tree.
15

Phylogenetic relationship of forest spiny pocket mice (Genus Heteromys) inferred from mitochondrial and nuclear markers with implications for species boundaries

Gonzalez, Malinda Wallentine 22 March 2005 (has links) (PDF)
I constructed a best estimate phylogeny based on congruence of multiple data sources. In recent years molecular data has been used both to construct phylogenies of taxonomic groups and to aid in the delimitation of new species. I generated and analyzed sequence data for forest spiny pocket mice (Genus Heteromys) for the mitochondrial gene cyt b (1143 bp) and two nuclear gene segments MYH2 (252 bp) and EN2 (189 bp). I used maximum parsimony and Bayesian analyses to infer relationships among species and to provide a framework for using a species delimitation method to investigate the possibility of multiple species within the widespread Heteromys desmarestianus. I found several well-supported lineages within the H.desmarestianus complex, including H. goldmani and H. oresterus. Incorporating karyotype and allozyme data from earlier studies, I found sufficient supporting evidence to justify maintaining H. goldmani and H. oresterus as species as well as identifying four lineages as candidate species. I present a revised taxonomic arrangement within the genus; the subgenus Heteromys should be divided into three species groups: anomalus (H. anomalus and H. australis), gaumeri (H. gaumeri), and desmarestianus (H. desmarestianus, H. goldmani, H. oresterus, and the four candidate species).
16

Partition Based Phylogenetic Search

Sundberg, Kenneth A. 04 August 2010 (has links) (PDF)
Evolutionary relationships are key to modern understanding of biological systems. Phylogenetic search is the means by which these relationships are inferred. Phylogenetic search is NP-Hard. As such it is necessary to employ heuristic methods. This work proposes new methods based on viewing the relationships between species as sets of partitions. These methods produce more parsimonious phylogenies than current methods.
17

Generaliseringsförmåga vid genetisk programmering

Svensson, Daniel January 2003 (has links)
<p>I detta arbete undersöks hur bestraffningsmetoder för att bestraffa storleken på GP-program påverkar generaliseringsförmågan. Arbetet grundar sig på ett arbete som Cavaretta och Chellapilla gjort, där de undersöker skillnaden i generaliseringsförmåga mellan bestraffningsmetoden ”Complexity Penalty functions” och ingen bestraffningsmetod.</p><p>I detta arbete har nya experiment gjorts med ”Complexity Penalty functions” och ”Adaptive parsimony pressure”, som är en annan bestraffningsmetod. Dessa bestraffningsmetoder har undersökts i samma domän som Cavaretta och Chellapilla och ytterligare i en domän för att ge en bättre bild av hur de generaliserar.</p><p>I arbetet visar det sig att användningen av någon av bestraffningsmetoderna ”Complexity Penalty functions” och ”Adaptive parsimony pressure” oftast ger bättre generaliseringsförmåga hos GP-program. Detta motsäger det Cavaretta och Chellapilla kommer fram till i sitt arbete. ”Adaptive parsimony pressure” verkar också vara bättre på att generalisera än ”Complexity Penalty functions”.</p>
18

Generaliseringsförmåga vid genetisk programmering

Svensson, Daniel January 2003 (has links)
I detta arbete undersöks hur bestraffningsmetoder för att bestraffa storleken på GP-program påverkar generaliseringsförmågan. Arbetet grundar sig på ett arbete som Cavaretta och Chellapilla gjort, där de undersöker skillnaden i generaliseringsförmåga mellan bestraffningsmetoden ”Complexity Penalty functions” och ingen bestraffningsmetod. I detta arbete har nya experiment gjorts med ”Complexity Penalty functions” och ”Adaptive parsimony pressure”, som är en annan bestraffningsmetod. Dessa bestraffningsmetoder har undersökts i samma domän som Cavaretta och Chellapilla och ytterligare i en domän för att ge en bättre bild av hur de generaliserar. I arbetet visar det sig att användningen av någon av bestraffningsmetoderna ”Complexity Penalty functions” och ”Adaptive parsimony pressure” oftast ger bättre generaliseringsförmåga hos GP-program. Detta motsäger det Cavaretta och Chellapilla kommer fram till i sitt arbete. ”Adaptive parsimony pressure” verkar också vara bättre på att generalisera än ”Complexity Penalty functions”.
19

Paleobiogeographic Analyses of Late Ordovician Faunal Migrations: Assessing Regional and Continental Pathways and Mechanisms

Lam, Adriane R. 25 August 2015 (has links)
No description available.
20

Phylogenetic Studies in the Lamiales with Special Focus on Scrophulariaceae and Stilbaceae

Kornhall, Per January 2004 (has links)
This thesis deals with plants from the flowering plant order Lamiales, and especially the two families Scrophulariaceae and Stilbaceae. Both families have their main geographical distribution in southern Africa. The thesis presents phylogenies of Scrophulariaceae s. lat. that can be used as a framework both for a future formal classification of the Scrophulariaceae and of allied taxa. A new circumscription of the tribe Manuleeae of Scrophulariaceae is presented including also genera earlier placed in the tribe Selagineae (sometimes recognised as a family of its own, Selaginaceae). Manuleeae now consists of the genera: Barthlottia, Chaenostoma, Chenopodiopsis, Dischisma, Glekia, Globulariopsis, Glumicalyx, Gosela, Hebenstretia, Jamesbrittenia, Limosella, Lyperia, Manulea, Manuleopsis, Melanospermum, Phyllopodium, Polycarena, Pseudoselago, Reyemeia, Selago, Strobilopsis, Sutera, Tetraselago, Trieenea and Zaluzianskya. The genera Sutera and Selago are given new circumscriptions; Sutera is divided into two genera, Sutera and Chaenostoma. Selago is circumscribed to contain also taxa that formerly have been placed in Microdon and Cromidon. A new circumscription and infrafamiliar classification of the family Stilbaceae is also presented. Stilbaceae will consist of the three tribes: Bowkerieae, consisting of the genera Anastrabe, Bowkeria and Ixianthes; Hallerieae, consisting of Charadrophila and Halleria; and Stilbeae, consisting of Nuxia and Stilbe. Furthermore, the genera Campylostachys, Euthystachys, Kogelbergia and Retzia are all included in the genus Stilbe. The results in the thesis are based on parsimony and Bayesian phylogenetic inferences of DNA sequence data. Further, morphological characters are analysed and compared to the molecular phylogenies.

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