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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.
21

Coevolution of Rhagoletis hosts and their parasitic wasps

Hamerlinck, Gabriela 01 July 2015 (has links)
Phytophagous (plant-feeding) insects are extremely species-rich and typically display tight host associations (meeting and mating on or near their host plant) with one or a small number of hosts. This specialized lifestyle can promote diversification through assortative mating, ultimately leading to genetically differentiated host races (host associated differentiation; HAD). It has been shown that HAD can cascade up to the parasitic wasps (parasitoids) that utilize the phytophagous insects as hosts. Cascading HAD occurs when there is genetic differentiation among parasitoids as a result of differential host plant use by their host insects. Thus, host switching can promote parasitoid diversification as well. Here, I present three studies designed to help understand aspects of parasitoid shifts to novel hosts and environments. All of the studies in this dissertation utilize the Rhagoletis complex of flies and their associated parasitoids. Specifically, I address i) the role of subtle trait variation and environmental context in predicting successful parasitoid host shifts; ii) whether parasitoid host discrimination (a trait that can influence host shifts) is an innate or learned behavior; and iii) whether contemporary patterns of host shifts among parasitoids are echoed by historical host shifts in cophylogenetic analyses of host and parasitoid genera? Towards my first aim, I present a phenomenological model developed to predict successful host shifts by parasitoids. The simulations of the model explore how environmentally mediated traits can affect successful parasitoid colonization of a new host. For my second aim, I hypothesize that behaviors impacting parasitoid host plant preferences host shifts will be genetically based rather than a learned behavior. Shifting to a new host plant has been shown to cause reproductive isolation in phytophagous insects because of strong fidelity with their host plant. Parasitoids, however, have no direct contact with the host plant as they develop entirely within the host insect. The differences in life history traits could result parasitoid host shifts being driven by random changes in host preferences. I present preliminary results suggesting that parasitoids preferentially respond to their ancestral host plant’s olfactory cues, suggesting that host preferences have a genetic basis. Finally, I present a cophylogenetic analysis of Rhagoletis hosts and their parasitoids. I find that cospeciation is the most common coevolutionary event, although there is evidence of recent host shifting that contributes to current parasitoid species diversity. The results of these studies can help us understand how host shifts can act as a potential mechanism driving diversification in parasitoids.
22

Niche Construction, Sustainability and Evolutionary Ecology of Cancer

January 2012 (has links)
abstract: In complex consumer-resource type systems, where diverse individuals are interconnected and interdependent, one can often anticipate what has become known as the tragedy of the commons, i.e., a situation, when overly efficient consumers exhaust the common resource, causing collapse of the entire population. In this dissertation I use mathematical modeling to explore different variations on the consumer-resource type systems, identifying some possible transitional regimes that can precede the tragedy of the commons. I then reformulate it as a game of a multi-player prisoner's dilemma and study two possible approaches for preventing it, namely direct modification of players' payoffs through punishment/reward and modification of the environment in which the interactions occur. I also investigate the questions of whether the strategy of resource allocation for reproduction or competition would yield higher fitness in an evolving consumer-resource type system and demonstrate that the direction in which the system will evolve will depend not only on the state of the environment but largely on the initial composition of the population. I then apply the developed framework to modeling cancer as an evolving ecological system and draw conclusions about some alternative approaches to cancer treatment. / Dissertation/Thesis / Ph.D. Applied Mathematics for the Life and Social Sciences 2012
23

Ecosystem Impacts of Consumer Evolution: Intraspecific Variation in the Elemental Phenotype of Aquatic Consumers

January 2017 (has links)
abstract: Primary production in aquatic ecosystems is often limited by the availability of nitrogen (N) and/or phosphorus (P). Animals can substantially alter the relative availability of these nutrients by storing and recycling them in differential ratios. Variation in these stoichiometric traits, i.e., the elemental phenotype, within a species can link organismal evolution to ecosystem function. I examined the drivers of intraspecific variation in the elemental phenotype of aquatic consumers to test for the generality of these effects. Over a thermal gradient in Panamá, I found that average specific growth grate and body P content of the mayfly Thraulodes increased with environmental temperature, but that these patterns were due to site-specific differences rather than the direct effects of warmer temperature. In a meta-analysis of published studies, I found that in fishes intraspecific variation in dietary N:P ratio had a significant effect on excretion N:P ratio, but only when accounting for consumption. I tested for the effects of variation in consumption on excretion N:P ratio among populations of the fish Gambusia marshi in the Cuatro Ciénegas basin in Coahuila, Mexico. G. marshi inhabits warm groundwater-fed springs where it often co-occurs with predatory fishes and cool runoff-dominated wetlands which lack predators. Using stoichiometric models, I generated predictions for how variation in environmental temperature and predation pressure would affect the N:P ratio recycled by fishes. Adult female G. marshi excretion N:P ratio was higher in runoff-dominated sites, which was consistent with predators driving increased consumption rates by G. marshi. This result was supported by a diet ration manipulation experiment in which G. marshi raised on an ad libitum diet excreted N:P at a lower ratio than fish raised on a restricted diet ration. To further support the impacts of predation on phenotypic diversification in G. marshi, I examined how body morphology varied among habitats and among closely related species. Both among and within species, predation had stronger effects on morphology than the physical environment. Overall, these results suggest that predation, not temperature, has strong effects on these phenotypic traits of aquatic consumers which can alter their role in ecosystem nutrient cycling through variation in consumption rates. / Dissertation/Thesis / Doctoral Dissertation Biology 2017
24

Ecologie évolutive de la transmission maternelle d'anticorps / Evolutionary ecology of the maternal transfer of antibodies

Garnier, Romain 15 December 2011 (has links)
Chez les vertébrés, la réponse immunitaire acquise représente un mécanisme sophistiqué de réponse face aux parasites dont l‟une des particularités est la possibilité qu‟il offre aux mères de transférer certains de ses effecteurs à leurs nouveau-nés. Pourtant, malgré un intérêt croissant pour les effets maternels, les déterminants écologiques et évolutifs du transfert d‟anticorps maternels n‟ont pas encore été beaucoup étudiés. L‟analyse d‟un cadre théorique spécialement développé pour inclure le transfert transgénérationnel d‟immunité montre que l‟évolution de la capacité à transférer une immunité temporaire aux jeunes dépend des caractéristiques de l‟hôte et du parasite. En particulier, l‟augmentation de l‟espérance de vie de l‟hôte favorise l‟évolution de réponses immunitaires acquises, et la protection conférée par ces réponses est aussi supposée durer plus longtemps chez les hôtes longévifs. En accord avec cette prédiction, une étude de vaccination transgénérationnelle chez une espèce d‟oiseau de mer longévive a permis de mettre en évidence une demi-vie des anticorps maternels particulièrement longue. Les conditions sociales sont aussi un élément clé, et chez une espèce de mammifère, j‟ai pu montrer qu‟elles permettent un élargissement du répertoire d‟anticorps maternels. Le transfert d‟anticorps maternels est aussi à même de modifier les dynamiques épidémiologiques et pourrait présenter un atout non négligeable si la vaccination était utilisée en conservation. Enfin, ce mécanisme pourrait être mis à profit pour estimer l‟exposition des mères, et ainsi inférer la dispersion entre différentes zones d‟habitat / In vertebrate species, acquired immune response represents a sophisticated protection mechanism against parasites that has the particularity of enabling mothers to transmit part of its effectors to their newborns. Yet, despite an increasing interest in maternal effects, ecological and evolutionary determinants of the transfer of maternal antibodies remain poorly studied. The analysis of a theoretical framework specially developed to include a transgenerational transfer of immunity show that the evolution of an ability to temporarily protect offspring depends on the characteristics of both the host and the parasite. In particular, increasing the life span of the host favors the evolution of acquired immune responses and increases the duration of the protection offered by these mechanisms. Accordingly, a transgenerational vaccination study in a long-lived seabird revealed a particularly long half-life of maternal antibodies. Social conditions also proved important in a mammal species as they can allow for the broadening of the repertoire covered by maternal antibodies. The transfer of maternal antibodies could also modify epidemiological dynamics and could bbe an interesting asset if vaccination was used as a conservation tool. Finally, this mechanism could be used to estimate the exposure of mother and thus infer the dispersal rate between different habitat patches.
25

Migration Ecology of Vermivora Warblers

Kramer, Gunnar Robert January 2021 (has links)
No description available.
26

The Evolution of Ecological Interactions During Adaptive Diversification in Pseudomonas Aeruginosa

Houpt, Noah 03 September 2021 (has links)
Ecological opportunity—the availability of open niche space to an evolving lineage—has long been thought to modulate the extent of adaptive diversification. Many microbial evolution experiments have confirmed that ecological opportunity drives diversification of initially homogeneous populations into communities of ecologically distinct sub-lineages (ecotypes). Interactions among ecotypes are crucial for both community function and the maintenance of the ecological diversity produced during adaptive diversification, however the factors influencing the evolution of these interactions remain unexplored. We assessed the influence of ecological opportunity on this process by studying communities of the bacterium Pseudomonas aeruginosa that were evolved in either nutritionally complex (COM) or simple (SIM) environments. We measured the net ecological interactions in these communities by comparing the cellular productivity and competitive fitness of whole communities from each environment to that of their component isolates in both complex and simple media. On average, COM communities had both higher productivity and fitness than their component isolates in complex media, indicating that the components of these communities share net positive interactions. The same was not true of SIM communities, which did not differ in either measure from their component isolates. Follow-up experiments revealed that high fitness in two COM communities was driven by rare variants (frequency < 0.1%) that secrete compounds during growth which inhibit PA14, the strain used as a common competitor for fitness assays. Taken together, our results suggest that environments with high levels of ecological opportunity drive diversification into ecotypes that share net positive ecological interactions. The strong effect of diversity on productivity and fitness we found in newly diversified communities has a number of implications for evolutionary ecology as well as the treatment of P. aeruginosa infections.
27

Temporal dynamics of resistance in an exotic plant Solidago altissima: geographic variation of plant-herbivore interactions in native and invaded range / 外来植物セイタカアワダチソウの抵抗性の時間的な動態:原産地と侵入地における植物-植食者相互作用の地理的変異

Sakata, Yuzu 23 March 2016 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第19529号 / 理博第4189号 / 新制||理||1601(附属図書館) / 32565 / 京都大学大学院理学研究科生物科学専攻 / (主査)教授 大串 隆之, 教授 中野 伸一, 教授 曽田 貞滋 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM
28

Associational anti-herbivore defense in the trichome dimorphism of Arabidopsis halleri subsp. gemmifera (Brassicaceae) / ハクサンハタザオ(アブラナ科)のトライコームによる被食防御における連合効果

Satou, Yasuhiro 23 March 2016 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第19536号 / 理博第4196号 / 新制||理||1602(附属図書館) / 32572 / 京都大学大学院理学研究科生物科学専攻 / (主査)教授 工藤 洋, 教授 田村 実, 教授 石田 厚 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM
29

Evolutionary ecology and discovery of new bioactive compounds from Lumnitzera mangroves across the Indonesian Archipelago

Manurung, Jeprianto 06 November 2023 (has links)
This thesis examines the biodiversity and evolutionary ecology of Lumnitzera mangroves in the Indonesian Archipelago. Using a combination of genomics and metabolomics, the study arrived at several key findings: (1) Investigation into 14 populations of L. littorea and 21 populations of L. racemosa revealed low genetic variation, with significant barriers like Sulawesi and the Java Sea influencing genetic differentiation. (2) Specifically for L. littorea, Wallace's line was identified as a key biogeographical separator, marking divergent evolutionary pathways and separating phylogroups, whereas L. racemosa showed a mixing population in the Wallacea region. (3) Uniquely, the research discovered a diversity in sulfated constituents, including previously unknown compounds like Lumnitzeralactone. (4) Further emphasizing the mangroves' medicinal importance, antibacterial potential was uncovered in the species. (5) The study innovatively linked phylogenetic data with chemical analyses, offering a comprehensive view of mangrove evolution and ecology. (6) Finally, the findings highlighted the need for specific conservation strategies, considering the genetic differentiation within populations, to protect the mangroves' ecological significance and medicinal value across Indonesia.:Preface 4 Summary 5 Zusammenfassung 10 1. Introduction 15 1.1. Characteristics, significance, and threat of mangroves 15 1.1.1. Characteristics of mangroves 15 1.1.2. Significance of Indonesian mangroves 16 1.1.3. Threats to mangroves 18 1.2. Evolutionary processes and diversity of mangroves 19 1.2.1. Evolution of mangroves 19 1.2.2. Sea surface currents in Indonesia shape genetic structure 20 1.2.3. The relevance of Wallace’s line to mangrove evolution 22 1.2.4. Isolation by geographical distance 24 1.2.5. Genetic diversity and population structure 25 1.3. Diversity of bioactive compounds of mangrove genus Lumnitzera 27 1.3.1. Sulfur-containing metabolites 27 1.3.2. Phylogenetics 28 1.3.3. Anti-infective potential 29 1.4. Study species 30 1.5. Aim of the thesis 33 2. Material and Methods 37 2.1. Sampling and sample design 37 2.2. Laboratory procedures and genetic analysis 38 2.2.1. DNA isolation 38 2.2.2. ddRADseq sequencing, and bioinformatics 38 2.2.3. Genetic diversity, population structure and differentiation 40 2.2.4. Identifying barriers and areas of connectivity 41 2.2.5. Isolation by distance and sea surface current connectivity 42 2.2.6. Polymerase Chain Reaction (PCR), and phylogenetic analyses 43 2.3. Laboratory procedures and phytochemical analysis 44 2.3.1. Root sample extraction 44 2.3.2. TLC, Low-resolution ESI-MS spectra, HPLC, and NMR 45 2.3.3. UHPLC-ESI-QqTOF-MS and MS/MS 46 2.3.4. RP-UHPLC-ESI-LIT-Orbitrap-MS 47 2.3.5. Extraction and isolation of compounds 47 2.3.6. Anti-infective bioassays 51 3. Results 52 3.1. Genetic diversity and population structure 52 3.1.1. Genetic diversity 52 3.1.2. Population structure and genetic differentiation 54 3.1.3. Effective migration 58 3.1.4. Isolation by distance and sea surface current connectivity 59 3.2. Unusual-sulfated constituent and anti-infective properties 61 3.2.1. Phytochemical screening 61 3.2.2. Phylogenetic tree of Lumnitzera 69 3.2.3. Evaluation of anti-infective properties 70 4. Discussion 74 4.1. Population genomics of Lumnitzera mangroves in Indonesia 74 4.1.1. The genetic diversity paradox in mangroves 74 4.1.2. Phylogroups and the Sunda-Wallacea biogeographical pattern 76 4.1.3. Limited mixture among phylogroups and populations by sea surface currents 78 4.1.4. Restricted gene flow by geographical distance 80 4.1.5. Evolutionary ecology of Lumnitzera inferred by genetics and chemodiversity 81 4.2. Bioactive compounds and anti-infective potential of Lumnitzera 82 4.2.1. Diversity of bioactive compounds 82 4.2.2. Sulfated and nonsulfated ellagic acid supported by phylogenetic pattern 83 4.2.3. Anti-infective properties and their restriction to particular locations 86 5. Conclusion and future perspective 89 6. References 94 7. Appendix 111 Curriculum vitae 119 Declaration of independent work 122 Acknowledgments 123 Author contributions statement 125 Authors’s Addendum / Diese Arbeit untersucht die biologische Vielfalt und evolutionäre Ökologie der Lumnitzera-Mangroven im indonesischen Archipel. Unter Verwendung einer Kombination aus Genomik und Metabolomik gelangte die Studie zu mehreren wichtigen Ergebnissen: (1) Die Untersuchung von 14 Populationen von L. littorea und 21 Populationen von L. racemosa ergab eine geringe genetische Variation, wobei signifikante Barrieren wie Sulawesi und die Javasee die genetische Differenzierung beeinflussen. (2) Speziell für L. littorea wurde die Wallace-Linie als wichtige biogeografische Trennlinie identifiziert, die divergierende Evolutionspfade markiert und Phylogruppen trennt, während L. racemosa eine Mischpopulation in der Wallacea-Region aufweist. (3) Einzigartig war die Entdeckung einer Vielfalt an sulfatierten Bestandteilen, darunter bisher unbekannte Verbindungen wie Lumnitzeralacton. (4) Ein weiterer Beleg für die medizinische Bedeutung der Mangroven ist das antibakterielle Potenzial, das in der Art entdeckt wurde. (5) Die Studie verknüpfte auf innovative Weise phylogenetische Daten mit chemischen Analysen und bot so einen umfassenden Einblick in die Evolution und Ökologie der Mangroven. (6) Schließlich verdeutlichten die Ergebnisse die Notwendigkeit spezifischer Erhaltungsstrategien, die die genetische Differenzierung innerhalb der Populationen berücksichtigen, um die ökologische Bedeutung und den medizinischen Wert der Mangroven in ganz Indonesien zu schützen.:Preface 4 Summary 5 Zusammenfassung 10 1. Introduction 15 1.1. Characteristics, significance, and threat of mangroves 15 1.1.1. Characteristics of mangroves 15 1.1.2. Significance of Indonesian mangroves 16 1.1.3. Threats to mangroves 18 1.2. Evolutionary processes and diversity of mangroves 19 1.2.1. Evolution of mangroves 19 1.2.2. Sea surface currents in Indonesia shape genetic structure 20 1.2.3. The relevance of Wallace’s line to mangrove evolution 22 1.2.4. Isolation by geographical distance 24 1.2.5. Genetic diversity and population structure 25 1.3. Diversity of bioactive compounds of mangrove genus Lumnitzera 27 1.3.1. Sulfur-containing metabolites 27 1.3.2. Phylogenetics 28 1.3.3. Anti-infective potential 29 1.4. Study species 30 1.5. Aim of the thesis 33 2. Material and Methods 37 2.1. Sampling and sample design 37 2.2. Laboratory procedures and genetic analysis 38 2.2.1. DNA isolation 38 2.2.2. ddRADseq sequencing, and bioinformatics 38 2.2.3. Genetic diversity, population structure and differentiation 40 2.2.4. Identifying barriers and areas of connectivity 41 2.2.5. Isolation by distance and sea surface current connectivity 42 2.2.6. Polymerase Chain Reaction (PCR), and phylogenetic analyses 43 2.3. Laboratory procedures and phytochemical analysis 44 2.3.1. Root sample extraction 44 2.3.2. TLC, Low-resolution ESI-MS spectra, HPLC, and NMR 45 2.3.3. UHPLC-ESI-QqTOF-MS and MS/MS 46 2.3.4. RP-UHPLC-ESI-LIT-Orbitrap-MS 47 2.3.5. Extraction and isolation of compounds 47 2.3.6. Anti-infective bioassays 51 3. Results 52 3.1. Genetic diversity and population structure 52 3.1.1. Genetic diversity 52 3.1.2. Population structure and genetic differentiation 54 3.1.3. Effective migration 58 3.1.4. Isolation by distance and sea surface current connectivity 59 3.2. Unusual-sulfated constituent and anti-infective properties 61 3.2.1. Phytochemical screening 61 3.2.2. Phylogenetic tree of Lumnitzera 69 3.2.3. Evaluation of anti-infective properties 70 4. Discussion 74 4.1. Population genomics of Lumnitzera mangroves in Indonesia 74 4.1.1. The genetic diversity paradox in mangroves 74 4.1.2. Phylogroups and the Sunda-Wallacea biogeographical pattern 76 4.1.3. Limited mixture among phylogroups and populations by sea surface currents 78 4.1.4. Restricted gene flow by geographical distance 80 4.1.5. Evolutionary ecology of Lumnitzera inferred by genetics and chemodiversity 81 4.2. Bioactive compounds and anti-infective potential of Lumnitzera 82 4.2.1. Diversity of bioactive compounds 82 4.2.2. Sulfated and nonsulfated ellagic acid supported by phylogenetic pattern 83 4.2.3. Anti-infective properties and their restriction to particular locations 86 5. Conclusion and future perspective 89 6. References 94 7. Appendix 111 Curriculum vitae 119 Declaration of independent work 122 Acknowledgments 123 Author contributions statement 125 Authors’s Addendum
30

SELECTIVE PREDATION DIFFERENTIALLY MODULATES ECOLOGICAL AND EVOLUTIONARY DISEASE DYNAMICS

Stephanie O Gutierrez (14216189) 06 December 2022 (has links)
<p>  </p> <p>Predators and parasites are critical, interconnected members of the community and have the potential to influence host populations. Predators, in particular, can have direct and indirect impacts on disease dynamics. By removing hosts and their parasites, predators alter both host and parasite populations and ultimately shape disease transmission. Our ability to accurately predict disease dynamics requires understanding the ecological effects of predation on prey and host densities and its role in the coevolution of host resistance and parasite virulence. While the impact of predators on disease dynamics has received considerable attention, research has focused on selective predation on infected prey. There is, however, substantial evidence that some predators avoid infected prey, preferentially attacking uninfected individuals. Such different strategies of prey selectivity by predators modulate host-parasite interactions, changing the fitness payoffs both for hosts and their parasites. I use empirical results and theoretical predictions as a framework to discuss the mechanisms by which predation for infected versus uninfected individuals can affect disease dynamics. First, by integrating hypotheses from behavioral ecology and disease ecology, I outlined novel perspectives that complement the prevailing view of selective predation of infected individuals (Chapter 1). Then, exploring short-term ecological outcomes and long-term host-parasite coevolution, I investigated patterns of <em>Daphnia dentifera</em> host population densities and host susceptibility over several generations under different types of predation pressure, including selective predation on infected and uninfected individuals (Chapter 2). Finally, building on the results of this research, I developed a high school project-based lesson plan that facilitates the instruction of the nature of science, implementing on-going ecological research in activities to improve student learning based on a constructivist approach to learning (Chapter 3). Together this research highlights the differential ecological and evolutionary outcomes of host-parasite interactions under varying community contexts.</p>

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