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Al-Mazrouai, Ahmed Mohammed. "Phenotypic plasticity in marine intertidal gastropods". Thesis, University of Plymouth, 2008. http://hdl.handle.net/10026.1/1973.
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Phenotypic plasticity, the differential phenotypic expression of the same genotype in response to different environmental conditions, is a paradigm central of the study of evolution and ecology and is at the core of the "nature versus nurture" debate. Here, the marine gastropod Littorina littorea was used as a model to further our understanding of the potential role of phenotypic plasticity in intertidal systems. In the first study L. littorea was included in an investigation of induced defences across six species of intertidal marine gastropods in the families Littorinidae and Trochidae. Species differed in the magnitude and type of plastic response, which appeared to relate to their susceptibility to crab predation. Chapters three and four revealed that L. littorea was able to alter its degree of morphological plasticity depending on temporal variation in predation threat. Snails exposed to predation threat halfway through trials appeared to "catch up" snails continuously exposed to predator cues in, terms of their shell size, whereas snails experiencing a removal of predation cues showed a significant reduction in growth rate following this switch in predation environment. A further investigation suggested that Littorina littorea demonstrated no significant difference in the morphological traits under variable predator threat versus a constant predator' threat environment. Finally, the interaction between biotic (predator) and abiotic (temperature) environmental effects revealed that snails maintained at 16 and 20° C demonstrated significant induced defences by growing larger and thicker shells, but there was no significant difference in induced defences between these two temperatures. However, the expression of induced defences was much lower at 24° C with only negative significant response in two of shell traits IV between control and predator cue treatments which may indicate that induced defences was inhibited at this temperature treatment. The implications of these results are discussed as is the potential applications of induced defences.
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Gold, Leslie. "Phenotypic plasticity of wetland species of Carex". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0031/MQ64363.pdf.
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Tibbits, Matthew Alan. "Scleractinian micromorphology : taxonomic value vs. phenotypic plasticity". Diss., University of Iowa, 2016. https://ir.uiowa.edu/etd/2155.
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Reef-building corals (Order: Scleractinia) are undergoing rapid taxonomic revision after molecular systematics disputed the relationships at all taxonomic levels within traditional classification. New morphological characters are being used to produce evolutionary relationships supported by molecular phylogenetics. While these characters are providing more congruent taxonomic relationships, their variation has not been fully explored. Additionally, phenotypic plasticity (changes in morphology resulting from environmental factors influencing the expressed phenotype despite a shared genotype) is prevalent amongst Scleractinia. In order to better understand the nature of these characters and explore their variation, I created a series of aquaria-based experiments designed to test the stability of these new morphological characters in response to differing environmental conditions. Light intensity and temperature were chosen as the environmental factors varied in these experiments on the basis of being a known trigger for environmentally-driven plasticity and their importance in calcification rate. In addition to aquaria-based phenotypic plasticity experiments I also examined a group (Family: Euphylliidae) within Scleractinia that had been divided by molecular phylogeny into two disparate groups. My research focused on morphological features viewed at magnifications observable by scanning electron microscopy (SEM) called micromorphology. Although variation in the skeletal micromorphology is observable, the new morphological characters that are used in taxonomy display only small amounts of variation caused by changing environmental conditions and were found to be stable for use in taxonomic studies. Additionally, I found a few micromorphological features distinguishing the two groups previously assigned to Euphylliidae including the shape of the septal margins and the fine-scale skeletal texture.
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Hooker, Oliver Edward. "The consequences of phenotypic plasticity on postglacial fishes". Thesis, University of Glasgow, 2016. http://theses.gla.ac.uk/7794/.
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Phenotypic differences within a species significantly contribute to the variation we see among plants and animals. Plasticity as a concept helps us to understand some of this variation. Phenotypic plasticity plays a significant role in multiple ecological and evolutionary processes. Because plasticity can be driven by the environment it is more likely to produce beneficial alternative phenotypes than rare and often deleterious genetic mutations. Furthermore, differences in phenotypes that arise in response to the environment can affect multiple individuals from the same population (or entire populations) simultaneously and are therefore of greater evolutionary significance. This allows similar, beneficial alternative phenotypes to increase quickly within a single generation and allow new environments to produce and select for new phenotypes instantly. The direction of the present thesis is to increase our understanding of how phenotypic plasticity, coupled with contrasting environmental conditions, can produce alternative phenotypes within a population. Plasticity provides a source of variation for natural selection to act upon, and may lead to genetic isolation as a by-product. For example, there are multiple cases of polymorphic populations of fish, where groups belonging to multiple isolated gene pools, have arisen in sympatry. Here it is shown that although plasticity is important in sympatric speciation events, plasticity alone is not responsible for the frequency in which sympatric polymorphic populations occur. The most frequently observed differences among sympatric polymorphic populations are morphological differences associated with parts of the anatomy used in the detection, handling and capture of prey. Moreover, it is shown here that there are physiological effects associated with foraging on alternative prey that may significantly contribute towards ecological speciation. It is also shown in this study that anthropogenic abiotic factors can disrupt developmental processes during early ontogeny, significantly influencing morphology, and therefore having ecological consequences. Phenotypic structuring in postglacial fish is most frequently based around a divergence towards either pelagic or littoral benthic foraging specialisms. Divergences that deviate from this pattern are of greater scientific interest as they increase our understanding of how evolutionary processes and selection pressures work. Here we describe a rare divergence not based around the typical pelagic/littoral benthic foraging specialisms. Finally, in this study, the effectiveness of local level conservation policy shows that species of fish which are highly variable in their life history strategies are harder to effectively manage and often poorly represented at a local level.
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Pascoal, Sónia Cristina Marques. "Nucella lapillus: imposex transcriptome analysis and phenotypic plasticity". Doctoral thesis, Universidade de Aveiro, 2011. http://hdl.handle.net/10773/4267.
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Doutoramento em BiologiaO conhecimento de mecanismos de genómica funcional tem sido maioritariamente adquirido pela utilização de organismos modelo que são mantidos em condições laboratoriais. Contudo, estes organismos não reflectem as respostas a alterações ambientais. Por outro lado, várias espécies, ecologicamente bem estudadas, reflectem bem as interacções entre genes e ambiente mas que, das quais não existem recursos genéticos disponíveis. O imposex, caracterizado pela superimposição de caracteres sexuais masculinos em fêmeas, é induzido pelo tributilestanho (TBT) e trifenilestanho (TPT) e representa um dos melhores exemplos de disrupção endócrina com causas antropogénicas no ambiente aquático. Com o intuito de elucidar as bases moleculares deste fenómeno, procedeu-se à combinação das metodologias de pirosequenciação (sequenciação 454 da Roche) e microarrays (Agilent 4*180K) de forma a contribuir para um melhor conhecimento desta interacção gene-ambiente no gastrópode Nucella lapillus, uma espécie sentinela para imposex. O trancriptoma de N. lapillus foi sequenciado, reconstruído e anotado e posteriormente utilizado para a produção de um “array” de nucleótidos. Este array foi então utilizado para explorar níveis de expressão génica em resposta à contaminação por TBT. Os resultados obtidos confirmaram as hipóteses anteriormente propostas (esteróidica, neuroendócrina, retinóica) e adicionalmente revelou a existência de potenciais novos mecanismos envolvidos no fenómeno imposex. Evidência para alvos moleculares de disrupção endócrina não relacionados com funções reprodutoras, tais como, sistema imunitário, apoptose e supressores de tumores, foram identificados. Apesar disso, tendo em conta a forte componente reprodutiva do imposex, esta componente funcional foi a mais explorada. Assim, factores de transcrição e receptores nucleares lipofílicos, funções mitocondriais e actividade de transporte celular envolvidos na diferenciação de géneros estão na base de potenciais novos mecanismos associados ao imposex em N. lapillus. Em particular, foi identificado como estando sobre-expresso, um possível homólogo do receptor nuclear “peroxisome proliferator-activated receptor gamma” (PPARγ), cuja função na indução de imposex foi confirmada experimentalmente in vivo após injecção dos animais com Rosiglitazone, um conhecido ligando de PPARγ em vertebrados. De uma forma geral, os resultados obtidos mostram que o fenómeno imposex é um mecanismo complexo, que possivelmente envolve a cascata de sinalização envolvendo o receptor retinoid X (RXR):PPARγ “heterodimer” que, até à data não foi descrito em invertebrados. Adicionalmente, os resultados obtidos apontam para alguma conservação de mecanismos de acção envolvidos na disrupção endócrina em invertebrados e vertebrados. Finalmente, a informação molecular produzida e as ferramentas moleculares desenvolvidas contribuem de forma significativa para um melhor conhecimento do fenómeno imposex e constituem importantes recursos para a continuação da investigação deste fenómeno e, adicionalmente, poderão vir a ser aplicadas no estudo de outras respostas a alterações ambientais usando N. lapillus como organismo modelo. Neste sentido, N. lapillus foi também utilizada para explorar a adaptação na morfologia da concha em resposta a alterações naturais induzidas por acção das ondas e pelo risco de predação por caranguejos. O contributo da componente genética, plástica e da sua interacção para a expressão fenotípica é crucial para compreender a evolução de caracteres adaptativos a ambientes heterogéneos. A contribuição destes factores na morfologia da concha de N. lapillus foi explorada recorrendo a transplantes recíprocos e experiências laboratoriais em ambiente comum (com e sem influência de predação) e complementada com análises genéticas, utilizando juvenis provenientes de locais representativos de costas expostas e abrigadas da acção das ondas. As populações estudadas são diferentes geneticamente mas possuem o mesmo cariótipo. Adicionalmente, análises morfométricas revelaram plasticidade da morfologia da concha em ambas as direcções dos transplantes recíprocos e também a retenção parcial, em ambiente comum, da forma da concha nos indivíduos da F2, indicando uma correlação positiva (co-gradiente) entre heritabilidade e plasticidade. A presença de estímulos de predação por caranguejos estimulou a produção de conchas com labros mais grossos, de forma mais evidente em animais recolhidos de costas expostas e também provocou alterações na forma da concha em animais desta proveniência. Estes dados sugerem contra-gradiente em alterações provocadas por predação na morfologia da concha, na produção de labros mais grossos e em níveis de crescimento. O estudo das interacções gene-ambiente descritas acima demonstram a actual possibilidade de produzir recursos e conhecimento genómico numa espécie bem caracterizada ecologicamente mas com limitada informação genómica. Estes recursos permitem um maior conhecimento biológico desta espécie e abrirão novas oportunidades de investigação, que até aqui seriam impossíveis de abordar.
Our understanding of functional genomic mechanisms is largely acquired from model organisms through laboratory conditions of exposure. Yet, these laboratory models typically have little environmental relevance. Conversely, there are numerous “ecological” model species that present important geneenvironment interactions, but lack genomic resources. Imposex, the superimposition of male sexual characteristics in females, is caused by tributyltin (TBT) and triphenyltin (TPT) and provides among the most widely cited ecological examples of anthropogenically-induced endocrine disruption in aquatic ecosystems. To further elucidate the functional genomic basis of imposex, combinations of 454 Roche pyrosequencing and microarray technologies (Agilent 4*180K) were employed to elucidate the nature and extent of gene-environment interactions in the prosobranch gastropod, Nucella lapillus, a recognized sentinel for TBT-induced imposex. Following transcriptome characterization (de novo sequencing, assembly and annotation), microarray fabrication and competitive hybridizations, differential gene expression analyses provided support for previously suggested hypotheses underpinning imposex (steroid, neuroendocrine, retinoid), but also revealed potential new mechanisms. Evidence for endocrine disruption (ED) targets such as the immune system, apoptosis and tumour suppressors other than reproduction-related functions were found; however, given the ED nature of imposex, primary focus was on gender-differentiation pathways. Among these, transcription factors and lipophilic nuclear receptors as transducers of TBT toxicity along with mitochondrial functions and deregulation in transport activity suggested new putative mechanisms for the TBT-induced imposex in N. lapillus. Particularly, up-regulation of a putative nuclear receptor peroxisome proliferator-activated receptor gamma (PPARγ) homolog was evident, and its role was further confirmed by inducing imposex in vivo using Rosiglizatone, a well-known vertebrate PPARγ ligand. Our analyses show that TBT-induced imposex is a complex mechanism, but is likely to act through the retinoid X receptor (RXR):PPARγ heterodimer signalling pathway, hitherto not described in invertebrates. Moreover, collectively, our findings support a commonality of signalling between invertebrate and vertebrate species that has previously been overlooked in the study of endocrine disruption. The genomic resources generated here largely contribute to the molecular understanding of imposex, yielding valuable insights for further examination of responses to TBT contamination exposure. Additionally, we anticipate that the new genomic resources described herein will contribute to the further exploration of adaptive responses of dogwhelks to environmental variation. N. lapillus was also used to explore adaptive shell shape morphology in response to natural variation in wave-action and crab predation. Knowledge of the contributions of genotype, plasticity and their interaction to phenotypic expression is crucial for understanding the evolution of adaptive character traits in heterogeneous environments. We assessed contributions of the above factors by reciprocal transplantation of snails between two shores differing in exposure to wave action and predation, and rearing snails of the same provenance in a laboratory common garden experiment with crab-predation odour, complemented by genetic analysis. The two target populations are genetically different but maintain the same karyotype. Truss-length and morphometric analyses revealed plasticity of shell shape in reciprocal transplants, but also the partial retention of parental shape by F2 snails in common garden controls, indicating co-gradient variation between heritable and plasticity components. Crab-predation odour influenced shell shape of snails from exposed-site origin and stimulated the production of thicker shell lips with greater response in snails of exposed-site ancestry. We interpret these data as countergradient variation on predator-induced changes in shell shape and increased thickening of the shell lip as well as on growth rates. The above exploration of gene-environment interactions demonstrates the feasibility, insights and novel opportunities that can now be addressed in a species that is well characterised ecologically, but hitherto constrained by the general lack of genomic tools and archived resources. Notably, a greater focus on detailed responses of a single species facilitates the comparative approach, as illustrated by the apparent commonality in regulation of endocrine disruption processes in invertebrates and vertebrates.
FCT; FSE - SFRH/BD/27711/2006
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Miner, Benjamin G. "Evolution of phenotypic plasticity insights from echinoid larvae /". Connect to this title online, 2003. http://purl.fcla.edu/fcla/etd/UFE0001450.
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Meyer, Aret. "Phenotypic plasticity of phages with diverse genome sizes". Diss., University of Pretoria, 2006. http://hdl.handle.net/2263/26157.
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A key factor in studying evolutionary biology is an understanding of the mechanisms organisms utilise in the ongoing process of adaptation. When faced with a heterogeneous and unpredictable environment, we expect organisms to evolve either as specialists or generalists, yet a unifying theory as to which will evolve is still lacking due to conflicting hypotheses based on limited empirical evidence. Phenotypic plasticity allows a single genotype to express different phenotypes, and has been found as an adaptive response to changing environments in all major taxa. With the advent of genomics it has become possible to study the underlying genetics of this phenomenon. It is however becoming clear that there is no single principle governing the plastic response, but rather a complex set of interactions between what appears to be regulatory and structural genes. With empirical data only recently becoming more readily available, the modelling of plastic responses are often still founded on the theoretical predictions and assumptions for which there is little proof. To bridge the gap between theory and nature, the challenge facing scientists today is the construction of experimental systems where theoretical predictions can be scrutinised. Given that phenotypic plasticity is a widespread phenomenon, understanding the magnitude and constraints of this response is an important issue in the study of evolution. Models have predicted a correlation between genome size and phenotypic plasticity, with increased genome size (complexity) linked to higher levels of phenotypic plasticity. Experimental findings, however, increasingly point to plasticity being governed by complicated sets of interactions between various parts of the genome, the adaptive landscape, and environmental cues. In the work presented here, a study was designed to test for a correlation between genome size and the level of plasticity by, looking at the fitness response of phages exposed to varying temperature. Seven phages differing in genome size and genome composition were used. Genome sizes ranged from 5386 bp to 170 000 bp. Taking advantage of the short generation times of phages, fitness could be measured as the growth rate per hour, which was compared among the different phage groups. The growth of large populations within a constant, controlled environment minimized the complications of environmental heterogeneity, and allowed for quantitative measure of the response to different temperatures. This was used to gain insight into how genome size relates to the level of phenotypic plasticity. Limited generation numbers were allowed for, to ensure population growth could be directly related to the plasticity of the genome, since numerous generations would be required for the effects of selection to become apparent. Adsorption rates are influenced by temperature, and were therefore measured to determine if it had a significant effect on the resulting population density. Results showed a marginal interaction between genome size and phenotypic plasticity, with adsorption rate having no significant effect. More experimental work would be required to verify this finding.Dissertation (MSc (Genetics))--University of Pretoria, 2006.
Genetics
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Leone, Stacy E. "Predator induced plasticity in barnacle shell morphology /". Abstract Full Text (HTML) Full Text (PDF), 2008. http://eprints.ccsu.edu/archive/00000496/02/1952FT.htm.
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Thesis (M.A.) -- Central Connecticut State University, 2008.Thesis advisor: Jeremiah Jarrett. "... in partial fulfillment of the requirements for the degree of Master of Arts in Biology." Includes bibliographical references (leaves 27-29). Also available via the World Wide Web.
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Crispo, Erika. "Interplay among phenotypic plasticity, local adaptation, and gene flow". Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:8881/R/?func=dbin-jump-full&object_id=92201.
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Kraft, Peter G. "The evolution of predator-induced phenotypic plasticity in tadpoles /". [St. Lucia, Qld.], 2004. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe18434.pdf.
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Worcester, Cynthia E. "Phenotypic Plasticity of Oral Jaw Dentition in Archosargus Probatocephalus". TopSCHOLAR®, 2012. http://digitalcommons.wku.edu/theses/1215.
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Phenotypic plasticity, the capacity of a single genotype to exhibit variable phenotypes in different environments, is common in many species. A sample of wild caught Archosargus probatocephalus, also known as sheepshead, from Florida was randomly divided into two treatment groups: one group was fed soft prey, Mercenaria sp. muscle tissue, and the other group was fed hard prey, Mercenaria sp. in the shell, for 365 days. It was hypothesized that the sheepshead fed hard prey would have a thicker tooth enamel layer containing more calcium, and therefore be stronger than the tooth enamel layer of those fed soft prey items. Additionally, the mean functional jaw surface area, the percentage of tooth coverage of functional jaw surface, number of teeth per jaw, correlation between standard length and mean total tooth height, and the combined surface area of the teeth, when compared between the two treatments, should be greater in the hard prey treatment.
The seventeen jaws of two prey groups were acquired postmortem and each jaw was divided into four quadrants. The largest tooth in each quadrant was removed from the jaw, longitudinally sectioned, and examined using scanning electron microscopy (SEM) to measure the enamel and dentin layers. Using the SEM backscatter electron detector the elemental composition of the different layers was determined at multiple locations. Finally, data was analyzed using analyses of variance (ANOVA’s) to compare mean tooth height, calcium content in enamel and dentin layers, mean functional jaw number of teeth per jaw, and upper to lower jaw overall enamel and dentin thickness between each treatment.
Phenotypic plasticity was identified in three areas: percentage of jaw surface covered by teeth, a positive correlation between total tooth height and enamel height in hard prey treatment, and a positive correlation between total tooth height and soft prey treatment dentin height; but not in the other areas studied. It is apparent that phenotypic plasticity can increase an individual’s ability to survive in a variable food resource environment by changing some aspects of tooth morphology, but the ability to change in response to stimuli was not found in all areas of tooth structure. i
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Pearson, Edmond Loring. "Induced phenotypic plasticity in the intertidal snail Nucella ostrina /". For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2004. http://uclibs.org/PID/11984.
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GAZZOLA, ANDREA. "Predator-induced phenotypic plasticity in anuran larvae and embryos". Doctoral thesis, Università degli studi di Pavia, 2016. http://hdl.handle.net/11571/1215975.
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La tesi di dottorato ha come obiettivo lo studio della plasticità fenotipica indotta dal rischio di predazione in anfibi anuri. L’organismo-preda modello è la Rana dalmatina, una specie locale facilmente reperibile, mentre il predatore è rappresentato da larve di Odonati del genere Anax e Aeshna e da predatori alloctoni.
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Habib, Farhat Abbas. "Genotype-phenotype correlation using phylogenetic trees". Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1187297400.
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Kopp, Michael. "Phenotypic plasticity from a predator perspective empirical and theoretical investigations /". Diss., Connect to this title online, 2003. http://edoc.ub.uni-muenchen.de/archive/00000916/.
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Ruehl, Clifton Benjamin. "Resource variation and the evolution of phenotypic plasticity in fishes". Thesis, Texas A&M University, 2004. http://hdl.handle.net/1969.1/486.
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Resource variation and species interactions require organisms to respond behaviorally, physiologically, and morphologically within and among generations to compensate for spatial and temporal environmental variation. One successful evolutionary strategy to mitigate environmental variation is phenotypic plasticity: the production of alternative phenotypes in response to environmental variation. Phenotypic plasticity yields multiple characters that may enable organisms to better optimize phenotypic responses across environmental gradients. In this thesis, I trace the development of thought on phenotypic plasticity and present two empirical studies that implicate phenotypic plasticity in producing morphological variation in response to resource variation. The first empirical study addresses trophic plasticity, population divergence, and the effect of fine-scale environmental variation in western mosquitofish (Gambusia affinis). Offspring from two populations were fed either attached or unattached food items offered in three orientations: (1) water surface, (2) mid-water, (3) benthic, and (4) a daily rotation of the former three (fine-grained variation). Attached food induced wide heads, blunt snouts and rounded pectoral fins relative to morphology in the unattached treatment. Mid-water feeding induced elongated heads and deeper mid-bodies relative to benthic and surface feeding induced morphologies. The rotating treatment produced intermediate morphologies. Population divergence seemed related to both trophic and predation ecology. Ecomorphological consequences of induced morphologies and the need for inclusion of greater ecological complexity in studies of plasticity are discussed. The second study examines induced morphological plasticity and performance in red drum (Sciaenops ocellatus). I fed hatchery fish either hard or soft food for two months. Performance trials were designed to measure their ability to manipulate and consume hard food items. External morphology and the mass of pharyngeal crushing muscles were assessed for variation among treatments. A hard food diet induced deeper bodies and larger heads, more massive pharyngeal muscles, and initially more efficient consumption of hard food than fish receiving soft food. The observed morphological variation is in accordance with variation among species. Determining evolutionary mechanisms operating within red drum populations should eventually aid in developing and optimizing conservation efforts and ease the transition from hatchery facilities to estuaries.
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Schrader, Lukas [Verfasser], i Jürgen [Akademischer Betreuer] Heinze. "Phenotypic plasticity in Cardiocondyla obscurior / Lukas Schrader ; Betreuer: Jürgen Heinze". Regensburg : Universitätsbibliothek Regensburg, 2015. http://d-nb.info/111387547X/34.
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Eilers, Wouter. "Sensory pathways of muscle phenotypic plasticity : calcium signalling through CaMKII". Thesis, Manchester Metropolitan University, 2012. http://e-space.mmu.ac.uk/315671/.
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Skeletal muscle can adapt its structure to cope with the mechanical and metabolic stresses placed on it by various amounts and patterns of human movement. The release of calcium into the cytoplasm of muscle fibres is thought to have an important role in these adaptations, yet the calcium-dependent signalling pathways involved haven’t been fully defined. Calcium/calmodulin-dependent protein kinase II (CaMKII) has been presumed to drive mitochondrial biogenesis in skeletal muscle, but this has not been investigated in vivo. The experiments in this thesis aimed to address how CaMKII is activated in response to electrical stimulation of skeletal muscle and how CaMKII affects the muscle phenotype. A rat model was used for two main reasons: 1) it allowed for imposing well-defined stimulation patterns onto phenotypically homogenous muscle fibre populations under controlled conditions in situ, and investigating the molecular response to these stimulation patterns, and 2) it allowed for manipulation of CaMKII signalling in muscle fibres in vivo through the use of electro-assisted somatic gene transfer. It was hypothesised that CaMKII would be activated in a muscle and recruitment pattern specific manner. Furthermore, it was hypothesised that CaMKII overexpression would increase the expression of mitochondrial markers. In chapter 2, the effect of recruitment frequency on CaMKII phosphorylation in slow-twitch m. soleus and fast-twitch m. gastrocnemius medialis is investigated. Furthermore, the time course of CaMKII phosphorylation after muscle stimulation is studied. Chapter 3 presents a study into the effects of in vivo CaMKII overexpression in m. soleus and m. gastrocnemius on mitochondrial gene expression and muscle contractile function. The effects of CaMKII overexpression on skeletal alpha-actin transcription are presented in chapter 4. In chapter 5, a mathematical model of CaMKII activation in sarcomeres is described, and used to investigate the effects of CaMKII overexpression on calcium handling and on contractile properties of a muscle fibre. It was concluded that CaMKII is activated by very brief stimulation in a recruitment frequency-independent manner, and that increased CaMKII protein levels increase SERCA expression, but not mitochondrial gene expression.
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Melin, Jerker. "Phenotypic plasticity of blue mussels under threat from different predators". Thesis, Uppsala universitet, Institutionen för biologisk grundutbildning, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-316376.
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My study confirms that there are phenotypic plastic traits in blue mussels (Mytilus edulis) inresponse to predatory pressure from shore crabs (Carcinus maenas) and sea stars (Asteriasrubens) and a combination of them. Blue mussels can sense predators by olfactory cues fromthe predators themselves, or by alarm cues from attacked conspecifics, and then developinducible defences. In this experimental study, blue mussels were exposed to either nopredator (control) or to enclosed predators in terms of two shore crabs, two sea stars or thecombination of one shore crab and one sea star, over a period of six weeks. According to previous studies a good defence against predation from shore crabs should be athicker and also a more circular mussel shell, and a good defence against sea stars should be astrong posterior adductor muscle. All three predatory treatments resulted in mussel individuals with significantly heavier shells.When exposed to sea stars, individuals grew less lengthwise and showed a significantly lowerend volume, as well as a significantly heavier posterior adductor muscle. These mussels alsoshowed a tendency to survive sea star predation better in the predation test. Thus, induciblephenotypic defences against predation by sea star predation, were clearly demonstrated. Theexposure to shore crabs resulted in a significantly higher height of the mussels, whencontrolling for mussel length. The mussels exposed to shore crabs also showed end volumessimilar to control mussels, whereas an exposure to a combination of a crab and a sea starresulted in intermediate end volumes. This supports a phenotypic plasticity in traits related topredator threat. Individuals in all three predatory treatments were harder attached by morebyssus threads at the end of the experiment. Control mussels and those exposed to a singlecrab and sea star were repeatedly found to be more aggregated (i.e. fewer solitary mussels)over the course of the experiment, whereas the mussels presumably exposed to more olfactorycues from two shore crabs or two sea stars were more often found solitary and attached bybyssus threads. This study demonstrated inducible defences in how blue mussel allocate their resources todifferent dimensions of growth, shell weight, adductor muscle weight, as well as aggregationand byssus attachment, depending on predatory threat.
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Bell, Emily Frances. "Phenotypic plasticity and the evolution of castes in eusocial insects". Thesis, University of Bristol, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.702895.
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Fernandes, Kenya Euphemia. "Phenotypic plasticity in Cryptococcus: clinical outcome & alternative antifungal therapy". Thesis, University of Sydney, 2020. https://hdl.handle.net/2123/23129.
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Cryptococcosis, caused by pathogenic yeasts of the Cryptococcus neoformans/ gattii complex, is a fungal disease associated with high mortality rates due in part to an incomplete knowledge of host-pathogen interactions, and a lack of effective antifungals. The aims of this thesis were therefore firstly to investigate the ability of Cryptococcus for phenotypic variation and determine how this affects pathogenicity and clinical outcome, and secondly, to evaluate and develop the antimicrobial compound lactoferrin (LF) as an antifungal for use in future treatments against Cryptococcus. In the first part of this study, virulence-associated phenotypes were found to differ in a species-specific manner in the C. gattii complex. In C. neoformans, an association between the capacity to make different cell types and clinical outcome was found, indicating that strains capable of greater variation may be more able to sustain infection and resist the host response. Together, these results illustrate the importance of cellular plasticity to host-pathogen interactions. In the second part of this study, LF was found to be active across yeast species primarily due to iron chelation, however synergy with antifungal drug amphotericin B (AMB) was independent of iron. In combination, LF+AMB disrupted biofilms, reduced Cryptococcus cell and capsule size and successfully treated infection in an in vivo wax moth model. Enzymatic digestion of LF produced a hydrolysate with substantially improved synergy and a novel 30-residue peptide dubbed lactofungin (LFG) was identified and synthesised. Antifungal susceptibility testing revealed LFG to be a successful synergent with AMB, outperforming whole LF and requiring lower AMB dosages. Overall, this thesis has provided insight into the relationship between phenotypic variation and virulence with potential significance to clinical outcome and has identified a novel drug lead with the potential to be developed for use in future antifungal therapies.
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Van, de Ven Tanja Maria Francisca Nicole. "Phenotypic plasticity of metabolic rate in an afrotropical bird species (Euplectes orix) across a temperature gradient". Thesis, Nelson Mandela Metropolitan University, 2012. http://hdl.handle.net/10948/d1012659.
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Avian species are known to have the capacity to respond to environmental changes through physiological adjustments. The process whereby organisms adjust their phenotype without genetic change is termed phenotypic plasticity and it is mostly observed to be a phenotypic improvement to ecological challenges. Metabolic rate (MR), which is the rate of energy expenditure in a species, is a highly flexible physiological parameter which results in a great diversity of avian standardised metabolic rates. Like birds from high latitudes, Afrotropical bird species are expected to have the capacity to adjust their energy expenditure to match the availability of resources. Previous studies on the flexibility of physiological parameters in birds have focused on the magnitude of change of physiological adjustments and the cues inducing these changes. Comparative research has furthermore investigated metabolic rates across aridity, altitude, latitude and temperature gradients. Recently, a clear dichotomy has become evident with elevated metabolic rates observed in high latitude birds in winter and a down-regulation of metabolic rates observed in birds exposed to low latitude mild winters. In this study, the shape of the reaction norm, the magnitude, the reversibility, the direction and the rate of change of two physiological parameters, basal metabolic rate (BMR) and summit metabolic rate (Msum), were investigated in a coastal and an inland population of Southern Red Bishops (Euplectes orix) through seasonal acclimatisation and laboratory acclimation. Summer and winter basal metabolic rates as well as body mass, were highly flexible traits in free-ranging coastal and inland Red Bishops. Birds acclimatised to a mild coastal climate in winter exhibited reduced basal and summit metabolic rates, whereas birds originating from a more variable inland climate increased basal metabolic rate in winter, but did not show increases of Msum in winter. Red Bishops responded to short term thermal acclimation under laboratory conditions by gradually changing body mass. Acclimation periods of 21 days revealed a negative relationship between body mass and acclimation air temperature. Peak responses of basal metabolic rate to ambient temperature change were observed in both coastal and inland birds between two and eight days after the change in acclimation air temperature. The influences of seasonal acclimatisation on energy expenditure differed between coastal and inland birds, however, during laboratory acclimation individuals from the two populations showed no difference in response. Within the individuals of the coastal and inland Southern Red Bishops, phenotypic flexibility is observed in body mass, basal metabolic rate and summit metabolic rate as a response to environmental changes. This flexibility is thought to increase thermoregulatory capacities of the Southern Red Bishop in different habitats and climates.
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Pri-Tal, Benjamin M. "Genomic and Hormonal Components of Altered Developmental Pathways in the Annual Killifish, Austrofundulus limnaeus". PDXScholar, 2010. https://pdxscholar.library.pdx.edu/open_access_etds/167.
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The annual killifish, Austrofundulus limnaeus, may enter embryonic diapause at three distinct points of development, termed diapause I, II, and III. Previous studies suggest a role for steroid hormones in the regulation of diapause in annual killifish. This study concerns the hormonal and genomic components involved in the developmental decision to enter or escape diapause II from both a maternal and embryonic perspective. Steroid hormone levels were measured in tissues isolated from adult female fish that were producing either high or low proportions of escape embryos. Levels of steroid hormones were also measured in new fertilized embryos that were known to be on either an escape or diapausing developmental trajectory. In addition, cDNA microarray gene expression analysis was used to identify gene sequences that may be associated with the regulation of entry into diapause in this species. Decreases in maternal estrogen levels associated with aging are correlated with decreasing escape embryo production, but there is no direct association between measured steroid hormone levels and escape embryo production. However, maternal production of escape embryos is correlated with increased ratios of 17 ß-estradiol to testosterone in ovary tissue, and cDNA microarray gene expression analysis indicates differentially regulated sequences associated with escape embryo production in maternal tissues. Both of these independent measures suggest hormonal involvement in the regulation of diapause. Embryonic levels of steroid hormones in newly fertilized embryos are not correlated with entry or escape from diapause II, although incubation in exogenous cortisol and 17 ß-estradiol causes an increase in the proportion of escape embryos. Gene expression analysis again suggests hormonal involvement. Interestingly, genes involved in epigenetic control of gene expression though chromatin condensation are differentially regulated in both maternal tissues producing escape embryos, and in embryos on the different developmental trajectories. These data suggest that hormonal control of gene expression through alterations of chromatin condensation may regulate the decision to enter or escape diapause II.
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Hegrenes, Scott Grayson Juliano Steven A. "Diet-induced phenotypic plasticity of feeding morphology in the genus Lepomis". Normal, Ill. Illinois State University, 1999. http://wwwlib.umi.com/cr/ilstu/fullcit?p9942644.
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Thesis (Ph. D.)--Illinois State University, 1999.Title from title page screen, viewed July 24, 2006. Dissertation Committee: Steven A. Juliano (chair), Wayne A. Riddle, Scott K. Sakaluk, Charles F. Thompson, Douglas W. Whitman. Includes bibliographical references (leaves 126-133) and abstract. Also available in print.
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Lind, Martin. "Phenotypic plasticity and local adaptation in island populations of Rana temporaria". Doctoral thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-26936.
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Phenotypic plasticity is the ability of a genotype to express different phenotypes in different environments. Despite its common occurrence, few have investigated differences in plasticity between populations, the selection pressures responsible for it, and costs and constraints associated with it. In this thesis, I investigated this by studying local adaptation and phenotypic plasticity in populations of the common frog Rana temporaria, inhibiting islands with different pool types (temporary, permanent or both). The tadpoles develop in these pools, and have to finish metamorphosis before the pool dries out. I found that the tadpoles were locally adapted both in development time and in phenotypic plasticity of development time. Tadpoles from islands with temporary pools had a genetically shorter development time than tadpoles from islands with permanent pools. The population differentiation in development time, estimated as QST, was larger than the population differentiation in neutral molecular markers (FST), which suggest that divergent selection among the populations is responsible for the differentiation. Moreover, tadpoles from islands with more variation in pool drying regimes had higher phenotypic plasticity in development time than tadpoles from islands with only one pool type present. Interestingly, increased migration among populations did not select for increased plasticity, rather it was the local environmental variation that was important. This adaptation has occurred over a short time scale, as the islands are less than 300 generations old. In temporary pools, it is adaptive to finish development before the pool dries out. This could be achieved by entering the metamorphosis at a smaller size, as a smaller size takes shorter time to reach. However, I found that there is a minimum threshold size below which tadpoles’ cannot enter metamorphosis, and that there had been no evolution of this threshold size in populations living in temporary environments. That suggests that this developmental threshold is tightly linked to physiological constraints in the developmental process. Despite their expected importance as constrains on the evolution of plasticity, costs of plasticity are often not found in nature. However, theories of why they are absent have not been tested empirically. In this thesis, I show that fitness costs of phenotypic plasticity are only found in populations with genotypes expressing high levels of phenotypic plasticity, while in populations with low-plastic genotypes, I find costs of not being plastic. This suggests that costs of plasticity increase with increased level of plasticity in the population, and that might be a reason why costs of plasticity are hard to detect.
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Boman, Jesper. "Genome size and phenotypic plasticity in the seed beetle, Callosobruchus maculatus". Thesis, Uppsala universitet, Institutionen för biologisk grundutbildning, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-337280.
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It has long been evident that genome size is not an accurate measure of organismal complexity. This paradox was “solved” with the discovery of nonfunctional and selfish DNA in the 1970s. However, emerging from this explanation was an enigma of complexity. Neither neutral nor adaptive models can account for all genome size variation across the tree of life. An organism with intraspecific variation is needed to investigate the functional role of genome size differences. Here I use different populations of the seed beetle, Callosobruchus maculatus, with a known intraspecific genome size variation of ~4%. It has previously been shown that a larger genome is associated with higher scores in fitness-related traits for this species. In this study, genome size is regressed with phenotypic plasticity along three different environmental gradients. Genome size did not correlate with plasticity in mass and development time along environmental gradients of temperature and host types. However, the results show that larger genomes are consistent with higher canalization of fitness under different food regimes. This further supports the idea that natural selection acts on genome size variation in this species.
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Aldous, Allison. "Phenotypic plasticity in three species of Cyperus with contrasting mating systems". Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=55477.
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One postulated prerequisite for phenotypic plasticity to evolve in a population is gene flow among its members. To test this hypothesis, I compared the phenotypic plasticity of 3 congeneric nut-sedges (Cyperus: Cyperaceae) that are similar in size, cohabit sandy beaches, yet differ in their reproductive strategies. Cyperus strigosus reproduces sexually by seed, C. dentatus asexually by bulbils, tubers, and rhizomes, and C. esculentus by a combination of sexual seed and asexual rhizomes and tubers. I predicted that C. strigosus and C. esculentus would be most plastic due to their potential for gene migration, while the asexual C. dentatus would be less plastic. Progeny arrays from nine genotypes of each species were grown in a series of eight environments in growth chambers. I measured 15 vegetative and reproductive traits at maturity. Analysis of covariance indicated a plastic response to the environment for all traits as well as genetic variation in phenotypic plasticity for all but vegetative allocation traits. Indices of plasticity for each genotype were highest for C. esculentus genotypes for vegetative traits and for C. strigosus genotypes for reproductive traits. These results support the hypothesis that non-zero gene migration enables the evolution of phenotypic plasticity.
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Durocher-Granger, Léna. "The effects of phenotypic plasticity on reproductive success of Trichogramma euproctidis". Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=104821.
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The body size of parasitoids varies with the amount of resources contained in a single host and this phenotypic plasticity applies to their reproductive traits. The impact of this phenotypic plasticity on the reproductive success of the egg parasitoid Trichogramma euproctidis in context of competition has been investigated. This species has been chosen for this study because different aspects of the reproductive strategies of both males and females are well known.Phenotypic plasticity in reproductive traits was observed in T. euproctidis. Results show that sperm size, and oocyte volume and number increased with body size. An index of maternal investment was calculated to determine how the effort invested in reproduction by females varies with body size and suggests that larger females invested more resources in reproduction. The plasticity in reproductive traits in T. euproctidis was a consequence of an environmental constraint of food availability, suggesting that resources acquisition during larval stage is a determinant factor of fitness. In context of sperm competition, smaller sperm were able to fertilize eggs earlier in an oviposition sequence but that advantage was apparent only when small sperm were in numerical inferiority which indicates that smaller sperm can compensate by being more competitive. Oocyte volume did not influence the outcome of the larval competition, but the clutch of the second-ovipositing female was advantaged, suggesting an ovicidal behavior from the second female.Les parasitoïdes démontrent une variation dans leurs tailles corporelles lorsqu'ils sont contraints par la quantité de ressources contenue dans l'hôte. La plasticité phénotypique des caractères reproducteurs du parasitoïde des œufs Trichogramma euproctidis ainsi que son impact sur le succès de reproduction en contexte de compétition ont été étudiés. Cette espèce a été choisie pour cette étude parce que différents aspects des stratégies de reproduction des mâles et des femelles sont bien connus.Une plasticité phénotypique des caractères reproducteurs a été observée pour T. euproctidis. Les résultats ont montré que la longueur des spermatozoïdes, et le volume et le nombre d'oocytes augmentent avec la taille corporelle. Un indice d'investissement maternel a été calculé pour déterminer l'effort investi en reproduction en lien avec la taille corporelle des femelles et suggère que les femelles de grandes tailles investissent plus de ressources en reproduction. Dans cette étude, la plasticité des caractères reproducteurs chez T. euproctidis est une conséquence d'une contrainte environnementale de disponibilité de la nourriture, suggérant que l'acquisition des ressources pendant le stade larvaire est un facteur déterminant de la valeur adaptative.En contexte de compétition spermatique, les petits spermatozoïdes ont fertilisé les œufs plus tôt dans la vie des femelles que les longs spermatozoïdes, mais seulement lorsque les petits spermatozoïdes étaient en infériorité numérique indiquant qu'ils peuvent compenser en étant plus compétitifs. Le volume des oocytes n'a pas influencé les résultats de la compétition larvaire, cependant la progéniture de la deuxième femelle qui pond a été avantagée sur la première, suggérant un comportement d'ovicide de la deuxième femelle.
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Nussey, Daniel H. "Phenotypic plasticity and population genetic structure in a wild vertebrate population". Thesis, University of Edinburgh, 2005. http://hdl.handle.net/1842/15544.
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My thesis focuses on maternal phenotypic plasticity in two neonatal traits and population genetic structure at different spatial scales in a wild red deer (Cervus elaphus) population on the Isle of Rum, Scotland. Specifically, I present: • An analysis of offspring birth weight-spring temperature plasticity in female red deer using linear regression to measure individual reaction norms. I found evidence of variation in plasticity between females and show that early experiences of high population density reduce female plasticity. • The description of a mixed-effects linear model approach to analysing phenotypic plasticity from a reaction norm perspective, and application of this model to birth date in the Rum deer population. I use the model to examine variation in phenotypic plasticity between females and selection on plasticity at different population density levels. • An examination of population history and structure in red deer from across the Isle of Rum using mitochondria) DNA and microsatellite markers. Analysis revealed that deer in this introduced population came from geographically isolated ancestral populations, and there was genetic evidence for strongly male-biased dispersal. Recent management practices on the island may have led to spatial variation in effective male dispersal on Rum. • A comparison of fine-scale spatial genetic structure between male and female deer in the North Block study area using microsatellite markers and census data. There was evidence of structure at extremely fine spatial scales amongst females but not males, and a decline in the structure amongst females over time. • An analysis of the spatial distribution of different mtDNA haplotypes in male and female red deer across the North Block. There was evidence for spatial structuring of haplotypes in both sexes.
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Suarez-Bosche, Nadia Elisa. "Acclimation and phenotypic plasticity of echinoderm larvae in a changing ocean". Thesis, University of Southampton, 2011. https://eprints.soton.ac.uk/336450/.
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Echinoderms are keystone organisms that have representatives in virtually every marine ecosystem. They possess a number of features that makes them an excellent model system, namely 1) their susceptibility to changes in the chemistry of seawater and temperature 2) their ossified skeletons are major contributors to many carbonate formations 3) their variety of life history strategies that enable successful reproduction (e.g. asexual reproduction, fission, cloning and regeneration). In most parts of the ocean, CO2 and temperature co-vary, making it difficult to extrapolate isolated effects of any one variable to natural scenarios. Laboratory and field work was conducted to assess the physiological and biogeochemical response of sea urchin Psammechinus miliaris larvae to changes in water carbonate chemistry. This study used two approaches: 1) the incubation of the larvae with naturally CO2-enriched deep-seawater, and 2) the study of the effect of ocean acidification and ocean warming. It is reported that there was no effect of in situ naturally high CO2 seawater, or laboratory induced CO2 concentrations, on larval physiology or morphology. However, elevated CO2 was found to cause a decrease in fertilization and calcification. An increase in temperature appeared to counteract significantly the negative effect that high CO2 has on fertilization and biocalcification. Therefore, it is argued that the developmental stages of sea urchins may adapt to predicted ocean acidification and increasing temperature scenarios, which is advantageous to maintaining stability and survival of populations under environmental selection pressure. Furthermore, the regeneration capability of the Pacific seastar larvae Pisaster ochraceus and Orthasterias koehleri was investigated. The successful complete re-growth of the larvae can be considered a specific developmental strategy that facilitates the species’ survival. This research suggests that echinoderm larvae are resilient to conditions in a changing ocean, due to their high acclimation capabilities and to their reproduction life history strategies. In this context, echinoderms may be considered an evolutionary success.
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Lind, Martin I. "Phenotypic plasticity and local adaptation in island population of Rana temporaria /". Umeå : Department of Ecology and Environmental Science, Umeå University, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-26936.
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Bernot, Randall Joseph. "Ecological consequences of Daphnia phenotypic plasticity in a Great Plains reservoir /". Search for this dissertation online, 2003. http://wwwlib.umi.com/cr/ksu/main.
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Nakazawa, Takefumi. "Influences of phenotypic plasticity in reproductive behaviors on multi-species dynamics". 京都大学 (Kyoto University), 2008. http://hdl.handle.net/2433/136931.
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Silva, Farley William Souza. "Phenotypic plasticity and susceptibility to pathogens in Anticarsia gemmatalis (Lepidoptera: Noctuidae)". Universidade Federal de Viçosa, 2010. http://locus.ufv.br/handle/123456789/3911.
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Prophylactic investment in defense from parasites and pathogens involves a high cost. Thus, it is expected that organisms use this only when required, for example, when at high population densities, where the risk of parasite or pathogen transmission may be increased. If the infection risk for individuals increases with host density, it is expected that hosts subject to high densities evolve mechanisms of resistance, as proposed by the "density-dependent prophylaxis" (DDP) hypothesis. Tests of these predictions have been conducted in a wide range of insects, both in comparative studies, where species live at different densities and in experimental studies, where the host density is manipulated. In the latter case, however, tests have mostly been restricted to gregarious insects that present density-dependent phase polyphenism. For this reason, we chose to test these predictions in a solitary species, Anticarsia gemmatalis (Lepidoptera: Noctuidae), that presents features of gregarious insects. We showed a prophylactic response to increased conspecific densities in A. gemmatalis larvae. When at increased larval density, with the accompanying phenotypic change, there is a greater degree of encapsulation of the nylon filament, higher hemocyte numbers, but lower melanization. We showed that this response was a function, not only the density per se, but also of the contact among conspecifics. Thus, we showed that DDP is a more common phenomenon thatpreviously thought, occurring even in a species known as being solitary. Furthermore, the prophylactic responses in this species are not only densitydependent, but are more specifically contact- dependent. This may provide a new context to the DDP hypothesis; in which even solitary species may present plastic prophylactic responses at crowded moments.
Investimentos profiláticos em defesa a parasitas e patógenos envolvem um custo. Assim, é esperado que organismos os usem somente quando requeridos, por exemplo quando em altas densidades populacionais, onde o risco de transmissão de parasitas e patógenos pode ser aumentado. Se o risco para o individuo aumenta com a densidade populacional, é esperado que hospedeiros evoluam mecanismos de resistência, como proposto pela hipótese da "profilaxia densidade-dependente" (PDD). Testes dessas predições têm sido conduzidos em uma gama de insetos, seja em estudos comparativos onde espécies vivem em diferentes densidades ou em estudos experimentais onde a densidade do hospedeiro é manipulada. Nesse caso, no entanto, testes têm sido restritos a insetos gregários que apresentam o polifenismo de fase densidade-dependente. Por isso, nós escolhemos testar essas predições em uma espécie solitária que apresenta características de insetos gregários, Anticarsia gemmatalis (Lepidoptera: Noctuidae). Neste estudo, nós mostramos as repostas profiláticas de larvas de A. gemmatalis ao aumento da densidade de co-específicos. Quando em maiores densidades larvais, acompanhada de mudança fenotípica, há um maior grau de encapsulação do filamento de nilon, aumento no número de hemócitos, mas menor melanização. Nós mostramos que essas respostas foram função não só densidade per se, mas também do contato entre co-específicos. Dessa forma, nós mostramos que a PDD é um fenômeno mais comum que se pensava, ocorrendo mesmo em espécies conhecidas como sendo solitárias. Além disso, as respostas profiláticas nessa espécie não são só densidade-dependente, mas mais especificamente, contato-dependente. Isto fornece um novo contexto a essa hipótese, já que mesmo espécies solitárias podem apresentar respostas profiláticas ao aumento da densidade populacional.
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García, López Juan Antonio. "Genomic patterns and phenotypic plasticity in prokaryotes analyzed within an ecological framework". Doctoral thesis, Universitat Autònoma de Barcelona, 2009. http://hdl.handle.net/10803/42004.
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Chuong, Simon Dich Xung. "Phenotypic plasticity of stem elongation in Stellaria longipes, anatomical and biochemical studies". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ34949.pdf.
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Alghamdi, Ahmed. "Phenotypic plasticity and population differentiation in Suaeda maritima on a salt marsh". Thesis, University of East Anglia, 2012. https://ueaeprints.uea.ac.uk/42351/.
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Suaeda maritima (L) Dumort is a polymorphic annual species of the family Chenopodiaceae that in the UK occurs exclusively in coastal salt marshes. The main aim of this study has been to examine the phenotypic variations within and between its populations in the heterogeneous microenvironments of a salt marsh. Detailed field characterizations of the growth, seed production and seed heteromorphism of four Suaeda maritima populations at Stiffkey salt marsh were conducted over three consecutive years, revealing considerable consistent phenotypic variation between populations on the high marsh, high-marsh creek bank, upper low marsh, and low marsh. Field environmental heterogeneity was assessed by taking measurements of sediment salinity, water content, organic content, redox potential, elevation in the tidal frame and annual number of tidal inundations. They demonstrated that different Suaeda maritima populations do indeed experience divergences between their environments that could both affect the phenotypic responses of developing plants and constitute selection pressures for the evolution of genetically differentiated populations. Experiments involving seedling reciprocal transplantation in the field and seedling transplantation to uniform laboratory conditions revealed significant differences among populations in terms of survival, growth and fecundity parameters. Detailed experiments examining the effect of salinity, temperature, light and storage conditions on seed germination and dormancy also revealed seed dimorphism and significant variation in the germination behaviour among populations. Suaeda maritima populations exhibited substantial evidence of genetic differentiation (reflecting the complex heterogeneity in their natural microhabitats) and, therefore, it can be suggested that this differentiation reflects adaptive ability to colonize wider range of habitats along the environmental gradients. Key words: Suaeda maritima, Salt marsh, Microhabitat, Population differentiation, Phenotypic plasticity, Fecundity, Seed heteromorphism, Dormancy, Germination, Survival, Reciprocal transplantation, Spatial heterogeneity
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Birget, Philip Laurent Guillaume. "Evolutionary ecology of parasites : life-history traits, phenotypic plasticity, and reproductive strategies". Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/28805.
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Adaptive phenotypic plasticity, the ability of a genotype to give rise to different phenotypes in different environments, evolves to allow organisms to fine-tune their life-history traits according to the varying conditions they encounter during their lives. Reproductive investment - the manner in which organisms divide their resources between survival and reproduction - is well studied in evolutionary ecology because it is a key determinant of fitness. However, whilst plasticity in reproductive effort is well understood for free-living multicellular taxa (such as insects, birds, and mammals), the application of evolutionary theory for plasticity and life history strategies to unicellular parasites and pathogens is lacking. In this thesis, I use empirical and theoretical approaches to uncover how differential resource allocation to non-replicating, sexual stages (gametocytes) versus asexually replicating stages can be harnessed by the rodent malaria parasite Plasmodium chabaudi to maximise its fitness across the often very variable conditions it encounters during infections. Differential allocation between those stages is equivalent to the fundamental life-history trade-off between survival and reproduction because gametocytes are responsible for between-host transmission (i.e. reproduction of the infection) whereas asexual parasites mediate host exploitation and within-host survival. A suite of within-host models reveal that malaria parasites could gain considerable fitness benefits in the face of low levels of drug treatment if they reduce their investment into gametocyte production ("reproductive restraint"), thereby assuring the continuity of the infection and capitalising on opportunities for future transmission. In contrast, high levels of drug treatment typically select parasites to commit all of their resources to gametocyte production ("terminal investment"), to escape a host that does not offer much opportunity for future transmission. My experiments reveal that P. chabaudi increases both its reproductive investment and its asexual replication rate in anaemic hosts (i.e. host that have a low density of red blood cells), suggesting that parasites profit from host anaemia and can afford high investment in gametocytes ("affluent investment"). I also uncover plasticity in a number of traits that underpin asexual replication rate, including invasion preference for different ages of red blood cells, but it is plasticity in the number of progeny (merozoites) per infected cell that is the main contributor to asexual replication rate. My experiments also reveal genetic variance in plasticity of the life-history traits investigated, which has profound implications for their evolution. Furthermore, plastic modification of these traits is associated with minimal costs or constraints, so that parasites can rapidly match life-history traits appropriately to the within-host environment. Severe anaemia is one of the deadliest symptoms of malaria, so observing that virulence and infectiousness increases in anaemic hosts has also fundamental clinical implications. Finally, the empirical and theoretical observations of affluent investment, reproductive restraint and terminal investment match theoretical predictions of how organisms should behave in varying environments, confirming P. chabaudi as a useful model system to test life-history theory.
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Gilbert, Anthony L. "Selection and Plasticity: Novel Phenotypic Trajectories in the Era of Climate Change". Ohio University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1582216645558001.
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Luo, Jing. "The role of phenotypic plasticity in the invasiveness of three Taraxacum species". Columbus, Ohio : Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1237576621.
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Bhatia, Sugandha. "EMT & MET: Underpinning the phenotypic plasticity and chemoresistance in breast cancer". Thesis, Queensland University of Technology, 2020. https://eprints.qut.edu.au/180913/1/Sugandha_Bhatia_Thesis.pdf.
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This dissertation aims to identify the functional characteristics and genetic factors present within breast cancers that contribute to intratumoural heterogeneity and therapy resistance. The study utilises breast cancer cell line model systems to address epithelial-mesenchymal plasticity (EMP) at the cellular and functional level and underpins its role in cancer biology and chemoresistance. This research also interrogates the EMP programme in single cell-generated clones and through shRNA mediated functional drug screening assay identifies inhibitors that provides significant synergistic drug combinations. A comprehensive review of the drugs that can clinically target EMP was also consolidated.
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Magris, Martina. "Phenotypic plasticity in male sexually selected traits in response to social cues". Doctoral thesis, Università degli studi di Padova, 2018. http://hdl.handle.net/11577/3425756.
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Reproductive success of males is strongly influenced by their investment in costly sexually selected traits. Fitness returns, however, are often context-dependent and vary with demographic parameters such as sex ratio and population density. Under conditions of environmental variability, the ability to modulate reproductive decisions on the social context is highly beneficial. As a result, phenotypic plasticity of sexually selected traits is widespread. The aim of my study was threefold. Firstly, I worked to expand our current knowledge on phenotypic plasticity in sexually selected traits both empirically, through a test of the effect of female availability on male mating effort in the nursery web spider, and theoretically, through a literature review on the subject of strategic adjustments of ejaculate quality. Secondly, I evaluated costs and benefits of the anticipatory upregulation of sperm production observed in male guppies as a response to perceived mating opportunities. Finally, I investigated how post-copulatory processes may shape male mate choice. The two species used in my study, the guppy, Poecilia reticulata, and the nursery web spider, Pisaura mirabilis, are particularly suited to investigate phenotypic plasticity of sexually selected traits because they both express costly reproductive traits and they experience environmental fluctuations in socio-sexual factors. When I explored the effect of female availability on male investment in pre- and post-copulatory traits, I found that P. mirabilis males do not respond to variation in this parameter. While males do not reduce their mating effort per partner as mating opportunities increase, they may respond instead by increasing their total reproductive budget. The literature review focusing on plasticity of ejaculate quality, besides showing the diversity of traits subject to adjustment and of stimuli triggering the response, highlighted the difficulty of estimating the fitness consequences of ejaculate plasticity because of the complexity of patterns of co-variation with other reproductive and non-reproductive traits. The experiments investigating costs and benefits of anticipatory ejaculate adjustments showed that the costs of plasticity are minor in guppies, as compared to the costs of phenotype. Furthermore, the trade-off between sperm production and pre-copulatory traits (courtship rate) appears to be stronger than the trade-off between sperm number and quality. Finally, my experiments on post-copulatory processes demonstrated a first male sperm precedence and an advantage of previous partners against novel ones in multiply mated female guppies. These findings brought an important contribution to the understanding of phenomena of male mate choice, such as mate choice copying, audience effect and Coolidge effect. In conclusion, the results of my study demonstrate how trade-offs between pre- and post-copulatory traits have crucial effects on costs and benefits of phenotypic plasticity in reproductive traits, highlighting the importance to adopt an integrative approach and to consider multiple traits and their interaction when studying sexual selection. My results also stress the need for a careful evaluation of episodes of post-copulatory selection when interpreting plasticity of both pre- and post-copulatory investment.Il successo riproduttivo dei maschi è fortemente influenzato dal loro investimento in costosi tratti sottoposti a selezione sessuale. Tuttavia, i vantaggi in termini di fitness di tale investimento sono spesso condizione-dipendenti e variano al variare di parametri demografici quali la sex ratio e la densità di popolazione. In ambienti variabili, l’abilità di adattare le decisioni riproduttive al contesto sociale è altamente vantaggioso. Ne risulta che i tratti selezionati sessualmente sono frequentemente caratterizzati da plasticità fenotipica. L’obiettivo del mio studio era articolato in tre parti. In primo luogo, ho lavorato per espandere l’attuale conoscenza nel campo della plasticità fenotipica di tratti sottoposti a selezione sessuale, sia tramite un approccio sperimentale, testando l’effetto della disponibilità di femmine sullo sforzo riproduttivo di maschi di Pisaura mirabilis, sia tramite un approccio teorico, cioè raccogliendo la letteratura disponibile sul tema degli aggiustamenti strategici della qualità dell’eiaculato. In secondo luogo, ho valutato costi e benefici dell’aumento di produzione spermatica osservato nei maschi di guppy come risposta alla percezione di opportunità di accoppiamento. Infine, ho indagato l’effetto di processi post-copulatori su fenomeni legati alla scelta del partner. Le due specie utilizzate nel mio studio, il guppy, Poecilia reticulata, e il ragno P. mirabilis, sono particolarmente adatti per studiare la plasticità fenotipica di tratti sotto selezione sessuale in quanto entrambi esprimono costosi tratti riproduttivi e subiscono fluttuazioni del loro ambiente socio-sessuale. Lo studio degli effetti della disponibilità di femmine sull’investimento maschile in tratti pre- e post-copulatori ha rivelato che i maschi di P. mirabilis non rispondono a variazioni in questo parametro. Nonostante essi non riducano l’investimento riproduttivo allocato al partner all’aumentare delle opportunità di accoppiarsi, potrebbero invece rispondere aumentando il proprio budget riproduttivo totale. L’esame della letteratura sulla plasticità della qualità dell’eiaculato, oltre a mostrare la varietà dei tratti soggetti ad aggiustamenti e dei fattori di stimolo, ha evidenziato la difficoltà di stimare le conseguenze per la fitness di questo tipo di risposte, a causa della complessità dei pattern di interdipendenza con tratti riproduttivi e non. Gli esperimenti che hanno indagato costi e benefici degli aggiustamenti strategici dell’eiaculato hanno mostrato che in guppy i costi della plasticità sono ridotti, se confrontati con i costi del fenotipo. Inoltre, il trade-off tra produzione spermatica e tratti pre-copulatori (il tasso di corteggiamento) sembra essere più marcato di quello tra numero e qualità degli spermi. Infine, i miei esperimenti sui processi post-copulatori in femmine poliandriche hanno evidenziato una precedenza spermatica del primo maschio e un vantaggio dei partner precedenti rispetto a quelli nuovi. Queste scoperte portano un importante contributo alla comprensione di fenomeni osservati nel contesto della scelta maschile del partner, quali la copia della scelta, l’effetto audience e l’effetto Coolidge. In conclusione, i risultati del mio studio mostrano come i trade-off tra tratti pre- e post-copulatori abbiano importanti effetti sui costi e i benefici della plasticità fenotipica di tratti riproduttivi, evidenziando l’importanza di adottare un approccio integrativo e di considerare vari tratti e la loro interazione nello studio della selezione sessuale. I miei risultati sottolineano anche la necessità di un’attenta valutazione di episodi di selezione post-copulatoria durante l’interpretazione di casi di plasticità nell’investimento sia pre- e che post-copulatorio.
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Valley, Jenna. "Phenotyptic Plasticity in Larval and Juvenile Marine Invertebrates: Effects of Predators, Food, Gravity, and Sunlight". Thesis, University of Oregon, 2016. http://hdl.handle.net/1794/20714.
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Phenotypic plasticity, the ability of a single genotype to be expressed as a range of phenotypes in response to environmental variation, is a widespread phenomenon. Documented increasingly among the larval stages of marine organisms, phenotypic plasticity in the veliger larvae of the marine snail Littorina scutulata was investigated in response to predatory, nutritional, and gravitational stimuli.
Veligers developed rounder shells, smaller apertures, and reinforced aperture margins in response to water-borne cues from predatory crab larvae. The nature and degree of the induced-morphologies depended on cue composition and conferred decreased vulnerability to predation.
Food-limited veligers developed larger feeding and swimming structures (vela) with longer cilia relative to shell size compared to larvae raised with high food. This inducible offense corresponded with a decrease in vertical swimming speed, an unexpected result possibly reflecting behavioral manipulation of individual velar components. A cell proliferation assay indicated that growth of the larger structure was achieved partially by a steady rate of cell division over a longer period of time; an initially higher level of cell proliferation in veligers raised on high food dropped off sharply.
Velar lobe asymmetry, where one lobe is larger than the other, may exist to offset an asymmetry in weight distribution due to how the larval shell is carried. The larger velar
lobe overlies the protruding spire of the larval shell. Bi- and multi-lobed vela get bigger with shell size but follow different rules with regards to the relationship between velar asymmetry and shell asymmetry. Experimental alternations of mass distribution of the larval shell caused changes in the ratio of area between each side of the velum and total velar growth for larvae of L. scutulata.
Following settlement and metamorphosis, juveniles of intertidal marine invertebrates are subject to additional stressors that can manifest as phenotypic variation. Color differences between juvenile and adult Strongylocentrotus purpuratus were shown to be caused by variation in light exposure. Green juveniles raised in sunlight turned purple (due to more pigment) and showed decreased susceptibility to artificial UVR than urchins kept in the dark, which remained green (due to less pigment).
This dissertation includes previously unpublished co-authored material.
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Snell-Rood, Emilie Catherine. "Costs of Plasticity in Host Use in Butterflies". Diss., The University of Arizona, 2007. http://hdl.handle.net/10150/194797.
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Phenotypic plasticity, the ability of a genotype to express different phenotypes in different environments, allows organisms to cope with variation in resources and invade novel environments. Biologists have long been fascinated with the costs and tradeoffs that generate and maintain variation in plasticity, such as possible increases in brain size and delays in reproduction associated with the evolution of learning. However, the costs of plasticity vary: many studies have failed to find costs of plasticity, the degree of costs often vary with the system or environments considered, and many costs of plasticity are variable even within the lifetime of an individual. This research adopts a developmental perspective to predict the degree and incidence of costs of plasticity, using host learning in butterflies as a case study. Learning, a mechanism of plasticity that develops through a trial-and-error sampling process, should result in developmental costs and allocation of energy towards development (at the expense of reproduction). Furthermore, costs of learning should be less pronounced in environments for which organisms have innate biases and for learned traits underlain by short-term memory, relative to long-term memory (which requires more developmental re-structuring). This research found support for all three predictions across three levels of costs: behavioral costs, tissue costs, and fecundity trade-offs. Butterflies exhibited genetic variation in their ability to learn to recognize different colored hosts. Genotypes with higher proxies for long-term memory emerged with relatively larger neural investment and smaller reproductive investment. In contrast to these costs of long-term learning, proxies of short-term learning were only correlated with increased exploration of a range of possible resources (types of non-hosts) early in the host-learning process. Family-level costs of plasticity emerged from the ability to learn to locate a red host, for which butterflies do not have an innate bias. Costs of learning were also induced by learning itself: following exposure to novel (red) host environments, individual butterflies, regardless of genetic background, increased exploratory behavior, increased neural investment, and re-allocated energy away from reproduction towards other functions (e.g., flight). Considering developmental mechanisms helps to predict how costs will influence the evolution of learning and plasticity.
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Kulkarni, Saurabh S. "Endocrine Mechanisms Underlying Phenotypic Evolution in Frogs". University of Cincinnati / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1342106009.
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Marchal, Alexandre. "Larch hybrid vigor and role of the phenotypic plasticity in the construction of heterosis". Thesis, Orléans, 2018. http://www.theses.fr/2018ORLE2014/document.
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Le mélèze d'Europe (Larix decidua) est traditionnellement exploité pour son bois de qualité. Malheureusement, la culture de cette essence hors de son aire de distribution a été un échec. L'hybridation avec le mélèze du Japon (L. kaempferi) est une voie prometteuse, en particulier grâce à l'hétérosis manifesté par cet hybride. Au cours de cette dissertation, nous valorisons les données d'un diallèle multi-site intra- et inter-spécifique d'âge avancé. Le 1er chapitre présente l'analyse de traits de production et de qualité du bois. Nous confirmons ainsi l'hétérosis pour les traits liés au volume. Cet hétérosis n’entraîne pas de contrepartie en termes de qualité, et se montre stable d'un site à l'autre.Au contraire, d'autres traits ne présentent pas d'hétérosis, mais davantage d'héritabilité.Les performances additives pour ces traits sont stables d'un site à l'autre, et en espèce pure vs. en hybridation. Au cours du 2ème chapitre, nous nous intéressons au rôle de la plasticité phénotypique de traits de formation du bois dans la construction de l'hétérosis.Le mélèze hybride apparaît comme le taxon le plus plastique : tout comme ses espèces parentes, il produit un cerne de croissance étroit en conditions hydriques limitantes, mais sa croissance radiale surpasse celle de ses parents quand l'eau est abondante. Ce 2èmechapitre est également un premier pas vers la compréhension du rôle de la plasticité phénotypique dans la construction de l'architecture de la variance génétique entre la circonférence et la densité des troncs. Cette thèse se termine sur une synthèse, au cours de laquelle nous discutons les retombées de nos résultats pour l'amélioration du mélèze hybrideEuropean larch (Larix decidua) has been historically exploited within its natural rangefor its high quality wood, but the attempt to grow this species outside its native range was a failure. Hybridization with Japanese larch (L. kaempferi) is a promising path, in particular because of the heterosis this hybrid manifests. In this dissertation, we took advantage ofan old-enough, multi-site experiment with an inter-/intra-specific mating design. The first chapter presents the analysis of several traits involved in wood quality and productivity. We confirmed heterosis for volume related traits. The heterosis came with no counter part inwood quality, and it was stable across sites. Contrarily, some other traits showed no heterosis but higher heritabilities, and the additive performances for these traits were stable across sites and in pure species vs. in hybridization. In the second chapter, we investigated the role of phenotypic plasticity of some wood formation traits in the construction of the heterosis. Hybrid larch appeared as the most plastic taxon: it equaled the parental controls in producing narrow growth increments under drought, but it produced the largest rings in favorable water availability conditions. This second chapter was also a first step towards a better understanding of the role of phenotypic plasticity on the construction of the genetic variance architecture between larch stem circumference and density. The dissertation ends with a synthesis in which we discussed the implicationof our findings for the breeding of hybrid larch
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Hirsch, Philipp E. "Phenotypic Processes Triggered by Biological Invasions". Doctoral thesis, Uppsala universitet, Limnologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-158697.
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Individuals within a single population can vary widely in their phenotype e.g. in their body shape. These differences are an important source of biodiversity and they can precede evolutionary divergence within a population. In this thesis we use the biological invasion of the zebra mussels into Swedish lakes to investigate which processes create or maintain phenotypic diversity within populations of the two native fish species perch and roach and the mussel itself. Both fishes have specially adapted body shapes that depend on whether they feed in the near-shore or open-water habitat of lakes. This habitat-specific divergence was more pronounced in lakes with zebra mussels, probably because resources in both habitats were in higher supply due to the mussels’ effects on the lakes. Divergence in perch body shapes between habitats was also higher in lakes with a higher water clarity, suggesting that visual conditions can affect the resource use and thus also the expression of a habitat-specific body shape. When investigating the diversity of body shapes in the mussel itself we found that mussels from one lake changed their shell shape when exposed to different predators: fish predators induced a more elongated shell shape while crayfish predators induced a rounder shell. These specific shell shapes probably serve as two alternative predator defenses protecting the mussel from predation. We conclude that the availability and use of distinct resources is an important source of diversity within populations. Abiotic conditions can play a previously underappreciated role by promoting or impairing the use of the distinct resources thus affecting the divergence. The diversity of shell shapes we found in the zebra mussels complements our study by demonstrating that not only consumer responses to resources but also resources’ responses to predators can generate phenotypic diversity.
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Li, Xiaoshuang. "Identification and Phenotypic Plasticity of Metastatic Cells in a Mouse Model of Melanoma". FIU Digital Commons, 2017. http://digitalcommons.fiu.edu/etd/3472.
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Melanoma is the deadliest form of skin cancer due to its high propensity to metastasize and resistance to current therapies. We have created a spontaneous mouse model of metastatic melanoma (Dct-Grm1/K5-Edn3) where metastasis to the lungs is 80% penetrant. The primary tumors of these mice present cellular heterogeneity with cells at varying levels of differentiation. The main goal of this study was to determine the metastatic potential of the primary tumor resident Tyrosinase positive cells and evaluate the dynamic phenotypic changes as those cells move from the primary tumors to the sites of metastasis. To accomplish this aim I crossed the Dct-Grm1/K5-Edn3 mice to CreERT2/mT/mG mice to indelibly label Tyrosinase cell populations within the primary tumor with Green Fluorescent Protein (GFP) by topical application of 4-hydroxytamoxifen (4HT) at the tumor site. In vivo lineage tracing and characterization of GFP+ cells were performed in the metastatic lesions.
In the 4HT treated Dct-Grm1/ K5-Edn3/Tyr-CreERT2/mT/mG mice, primary tumor derived Tyrosinase positive cells or their progeny (GFP+) established successful metastases in the distant organs indicating the tumorigenic capacity of the differentiated cell populations. Numerous metastatic melanoma cells were identified in the vasculature of the metastatic organs and established close association with the vascular endothelium. The intravascular cells lost pigmentation and did not express melanocytic markers; however, they mimicked endothelial cell properties and gained the expression of CD31 (also known as platelet endothelial cell adhesion molecule PECAM-1) and vascular endothelial (VE)-Cadherin. In the lung metastatic foci, GFP+ cells resumed pigmentation production and lost the expression of endothelial cell markers. Evidence from other metastatic organs in the mice further supported the phenotypic plasticity of metastatic melanoma cells.
The in vivo lineage tracing system established in the melanoma mouse model revealed tumor phenotypic plasticity and will be a powerful model to evaluate and help us understand the etiology and pathogenesis of melanoma metastasis. Further characterization of those more aggressive cells in melanoma will allow for the development of new prognostic tests and novel therapeutic strategies to eliminate metastasis.
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Gardiner, Emmanuel. "Comparison of phenotypic plasticity in Bistorta vivipara in topographically rough and flat landscapes". Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for biologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-23290.
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Range shift in alpine plants:the study was intended to investigate if topographic effects on environmental conditions (soil moisture) will enhance plasticity in plants (alpine species). Thus, if topography will serve as a buffer shielding plants in heterogeneous landscapes against future environmental changes. If true, then climate change effects predicted to cause range shift in plants will have less impacts in alpine environments.
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Liu, Yanjie [Verfasser]. "The importance of phenotypic plasticity for plant success under environmental change / Yanjie Liu". Konstanz : Bibliothek der Universität Konstanz, 2017. http://d-nb.info/113964114X/34.
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