The Evolution and Genetics of Thermal Traits in Drosophila Melanogaster PDF Download
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Author: Lindsey Caroline Fallis
Publisher:
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Category :
Languages : en
Pages :
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Temperature is a critical environmental parameter and thermal variation has significant effects on local adaptation and species distributions in nature. This is especially true for organisms that are isothermal with their environment. Variation in temperature imposes stress and directly influences physiology, behavior, and fitness. Thus, to thrive across a range of thermal environments populations must contain sufficient genetic variation, the capacity to respond plastically, or some combination of both genetic and plastic responses. In this work I first quantified patterns of phenotypic and genetic variation in nature and then dissected the genetic basis of variation in thermal traits. In the first aim I used natural populations of Drosophila melanogaster collected from a latitudinal transect in Argentina to investigate variation in heat stress resistance and cold plasticity within and among populations. I found heat stress resistance was highly variable within populations, but was strongly associated with the monthly maximum average temperature of each site. For cold plasticity I was able to demonstrate significant variation in plasticity within and among populations, however the among population variation was best explained by the altitude of each site. I hypothesized that this was caused by a difference in temperature fluctuations at high altitude sites relative to low altitude sites. To evaluate this hypothesis I paired our study with existing laboratory data that demonstrated significant fitness differences between high and low plasticity (and altitude) sites when these populations were reared in variable thermal environments. Thus, cold plasticity is an adaptive response to environmental variation. The final project focused on understanding the genetic basis of thermal variation. I fine-mapped a single co-localized heat and cold tolerance QTL via deficiency and mutant complementation mapping to identify four novel thermal candidate genes. There was no overlap of the deficiencies or genes associated with cold or heat stress resistance. Sequence analysis of each gene identified the polymorphisms that differentiate the lines. To test for independent associations between these polymorphisms and variation in nature the Drosophila Genome Reference Panel was used to confirm associations between allelic variation and cold tolerance in nature.
Author: Lindsey Caroline Fallis
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Temperature is a critical environmental parameter and thermal variation has significant effects on local adaptation and species distributions in nature. This is especially true for organisms that are isothermal with their environment. Variation in temperature imposes stress and directly influences physiology, behavior, and fitness. Thus, to thrive across a range of thermal environments populations must contain sufficient genetic variation, the capacity to respond plastically, or some combination of both genetic and plastic responses. In this work I first quantified patterns of phenotypic and genetic variation in nature and then dissected the genetic basis of variation in thermal traits. In the first aim I used natural populations of Drosophila melanogaster collected from a latitudinal transect in Argentina to investigate variation in heat stress resistance and cold plasticity within and among populations. I found heat stress resistance was highly variable within populations, but was strongly associated with the monthly maximum average temperature of each site. For cold plasticity I was able to demonstrate significant variation in plasticity within and among populations, however the among population variation was best explained by the altitude of each site. I hypothesized that this was caused by a difference in temperature fluctuations at high altitude sites relative to low altitude sites. To evaluate this hypothesis I paired our study with existing laboratory data that demonstrated significant fitness differences between high and low plasticity (and altitude) sites when these populations were reared in variable thermal environments. Thus, cold plasticity is an adaptive response to environmental variation. The final project focused on understanding the genetic basis of thermal variation. I fine-mapped a single co-localized heat and cold tolerance QTL via deficiency and mutant complementation mapping to identify four novel thermal candidate genes. There was no overlap of the deficiencies or genes associated with cold or heat stress resistance. Sequence analysis of each gene identified the polymorphisms that differentiate the lines. To test for independent associations between these polymorphisms and variation in nature the Drosophila Genome Reference Panel was used to confirm associations between allelic variation and cold tolerance in nature.
Author: Margarida Matos
Publisher: Frontiers Media SA
ISBN: 2889664945
Category : Science
Languages : en
Pages : 152
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Author: K. Bijlsma
Publisher: Birkhäuser
ISBN: 3034888821
Category : Science
Languages : en
Pages : 328
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Most organisms and populations have to cope with hostile environments, threatening their existence. Their ability to respond phenotypically and genetically to these challenges and to evolve adaptive mechanisms is, therefore, crucial. The contributions to this book aim at understanding, from a evolutionary perspective, the impact of stress on biological systems. Scientists, applying different approaches spanning from the molecular and the protein level to individuals, populations and ecosystems, explore how organisms adapt to extreme environments, how stress changes genetic structure and affects life histories, how organisms cope with thermal stress through acclimation, and how environmental and genetic stress induce fluctuating asymmetry, shape selection pressure and cause extinction of populations. Finally, it discusses the role of stress in evolutionary change, from stress induced mutations and selection to speciation and evolution at the geological time scale. The book contains reviews and novel scientific results on the subject. It will be of interest to both researchers and graduate students and may serve as a text for graduate courses.
Author: Alison Renae Gerken
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Thermal stress impacts animals around the globe and understanding how organisms adapt to changes in temperature is of particular interest under current climate change predictions. My research focuses on the evolutionary genetics involved in cold tolerance and plasticity of cold tolerance using both artificially selected and naturally segregating populations, while tying the genes of interest to their physiological components. First I address cross-tolerance of stress traits following artificial selection to a non-lethal cold tolerance metric, chill-coma recovery. Using these artificial selection populations, we found that stress traits such as desiccation tolerance, starvation tolerance, acclimation, and chronic and acute cold tolerance do not correlate with level of cold tolerance as defined by chill-coma recovery time. We next assessed lifetime fitness of these different cold tolerance lines and found that only at low temperatures did fitness differ among cold tolerance levels. We then analyzed gene expression differences between resistant and susceptible populations at three time points to understand where selection pressures are hypothesized to act on genomic variation. Our gene expression analyses found many differences between resistant and susceptible lines, primarily manifesting themselves in the recovery period following cold exposure. We next utilized a community resource, the Drosophila melanogaster reference panel, to identify naturally segregating variation in genes associated with cold acclimation and fitness. We specifically asked if long- and short-term acclimation ability had overlapping genetic regions and if plasticity values from constant rearing environments were associated with demographic parameters in fluctuating environments. We found that long- and short-term acclimation are under unique genetic control and functionally tested several genes for acclimation ability. We also found that acclimation ability in constant environments and fitness in fluctuating environments do not correlate, but that genotypes are constrained in their fitness abilities between a warm and cool environment. Our analyses describe several novel genes associated with cold tolerance selection and long- and short-term acclimation expanding our knowledge of the complex relationship between demographic components and survivorship as well as a unique investigation of the change in gene expression during cold exposure.
Author: Michael J. Angilletta Jr.
Publisher: Oxford University Press
ISBN: 0191547204
Category : Science
Languages : en
Pages :
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Temperature profoundly impacts both the phenotypes and distributions of organisms. These thermal effects exert strong selective pressures on behaviour, physiology and life history when environmental temperatures vary over space and time. Despite temperature's significance, progress toward a quantitative theory of thermal adaptation has lagged behind empirical descriptions of patterns and processes. In this book, the author draws on theory from the more general discipline of evolutionary ecology to establish a framework for interpreting empirical studies of thermal biology. This novel synthesis of theoretical and empirical work generates new insights about the process of thermal adaptation and points the way towards a more general theory. The threat of rapid climatic change on a global scale provides a stark reminder of the challenges that remain for thermal biologists and adds a sense of urgency to this book's mission. Thermal Adaptation will benefit anyone who seeks to understand the relationship between environmental variation and phenotypic evolution. The book focuses on quantitative evolutionary models at the individual, population and community levels, and successfully integrates this theory with modern empirical approaches. By providing a synthetic overview of evolutionary thermal biology, this accessible text will appeal to both graduate students and established researchers in the fields of comparative, ecological, and evolutionary physiology. It will also interest the broader audience of professional ecologists and evolutionary biologists who require a comprehensive review of this topic, as well as those researchers working on the applied problems of regional and global climate change.
Author: Susanne Voigt
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Author: Zoltán Bochdanovits
Publisher:
ISBN: 9789039334324
Category :
Languages : en
Pages : 164
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Author: Quentin D. Sprengelmeyer
Publisher:
ISBN:
Category :
Languages : en
Pages : 139
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Drosophila melanogaster is a great model to use in untangling the evolutionary process of a novel trait. There are abundant molecular techniques, extensive genomic data, they have short generation time, and stocks can be maintained in the lab with relative ease. This dissertation uses these advantages to investigate the population history of D. melanogaster and the genetic basis of adaptive traits. Frist, I create a robust demographic model of D. melanogaster expansion throughout Africa and into Europe. Estimates from this analysis has this expansion throughout Africa starting ~13,000 years ago and crossing the Sahara relatively soon after and into Europe ~1,800 years ago. Second, I explore the genetic architecture of ethanol resistance found in multiple populations of D. melanogaster. Findings from this study include elevated ethanol resistance in three different populations and that ethanol and cold resistance may have a partially shared genetic basis. We also find that the genetic architecture of ethanol resistance evolution differs substantially not only between our three resistant populations, but also between two crosses involving the same European population. Finally, I investigate the evolution of two adaptive traits, thorax and wing size, found in a highland Ethiopia population. The results from this study show that genes with moderate to large and small effect contribute to both phenotypes and standing variation may have helped this population adapt to the novel habitat. We have also found there to variability in the genetic architecture within this population.
Author: V. Loeschcke
Publisher: Birkhäuser
ISBN: 3034885105
Category : Science
Languages : en
Pages : 427
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It follows naturally from the widely accepted Darwinian dictum that failures of populations or of species to adapt and to evolve under changing environments will result in their extinction. Population geneti cists have proclaimed a centerstage role in developing conservation biology theory and applications. However, we must critically reexamine what we know and how we can make rational contributions. We ask: Is genetic variation really important for the persistence of species? Has any species become extinct because it ran out of genetic variation or because of inbreeding depression? Are demographic and environmental stochas ticity by far more important for the fate of a population or species than genetic stochasticity (genetic drift and inbreeding)? Is there more to genetics than being a tool for assessing reproductive units and migration rates? Does conventional wisdom on inbreeding and "magic numbers" or rules of thumb on critical effective population sizes (MVP estimators) reflect any useful guidelines in conservation biology? What messages or guidelines from genetics can we reliably provide to those that work with conservation in practice? Is empirical work on numerous threatened habitats and taxa gathering population genetic information that we can use to test these guidelines? These and other questions were raised in the invitation to a symposium on conservation genetics held in May 1993 in pleasant surroundings at an old manor house in southern Jutland, Denmark.
Author: Kendall Mills
Publisher:
ISBN:
Category : Drosophila melanogaster
Languages : en
Pages : 44
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