Genomics and Physiological Evolution of Cold Tolerance in Drosophila Melanogaster PDF Download
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Author: Alison Renae Gerken
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
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: Alison Renae Gerken
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
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: Lindsey Caroline Fallis
Publisher:
ISBN:
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: K. Bijlsma
Publisher: Birkhäuser
ISBN: 3034888821
Category : Science
Languages : en
Pages : 328
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Book Description
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: Thomas Flatt
Publisher: OUP Oxford
ISBN: 0191621021
Category : Science
Languages : en
Pages : 506
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Book Description
Life history theory seeks to explain the evolution of the major features of life cycles by analyzing the ecological factors that shape age-specific schedules of growth, reproduction, and survival and by investigating the trade-offs that constrain the evolution of these traits. Although life history theory has made enormous progress in explaining the diversity of life history strategies among species, it traditionally ignores the underlying proximate mechanisms. This novel book argues that many fundamental problems in life history evolution, including the nature of trade-offs, can only be fully resolved if we begin to integrate information on developmental, physiological, and genetic mechanisms into the classical life history framework. Each chapter is written by an established or up-and-coming leader in their respective field; they not only represent the state of the art but also offer fresh perspectives for future research. The text is divided into 7 sections that cover basic concepts (Part 1), the mechanisms that affect different parts of the life cycle (growth, development, and maturation; reproduction; and aging and somatic maintenance) (Parts 2-4), life history plasticity (Part 5), life history integration and trade-offs (Part 6), and concludes with a synthesis chapter written by a prominent leader in the field and an editorial postscript (Part 7).
Author: Kylie Maureen Finnegan
Publisher:
ISBN:
Category : Drosophila melanogaster
Languages : en
Pages : 0
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Book Description
Rapidly changing climate conditions, including extreme temperature events, have wide-reaching implications for organismal adaptation. Organisms with complex life cycles can be differentially susceptible to physiological challenges posed by acute temperature stressors depending on developmental stage. Thus, sensitive life stages may act as a selective sieve through which species are differentially able to persist in a changing, warming world. Terrestrial ectotherms, such as the cosmopolitan Drosophila melanogaster, are dependent upon their external environment to dictate internal body temperature. The non-motile D. melanogaster embryo is entirely reliant upon innate physiological defense mechanisms to protect against and respond to the damaging effects of heat stress, given the inability to behaviorally thermoregulate. Early embryos (0-2 hours post fertilization) have been shown to display substantial differences in thermal tolerance between regionally distinct tropical and temperate populations. The rapid local adaptation seen in this trait is indicative of strong selection for the underlying favorable alleles. However, the underlying genetic basis of embryonic thermal tolerance is previously unknown. Previously, our lab used whole genome quantitative trait locus (QTL) mapping via a repeated backcrossing design to identify the genomic basis of differential embryonic thermal tolerance between flies of tropical vs. temperate origin. To determine the extent to which gene regulatory variation underlies embryonic thermal tolerance, I measured transcriptomic responses to heat stress using the same tropical, temperate, and advanced introgression lines that were used in the QTL mapping study. I identify 212 differentially expressed genes between the three genotypes (tropical, temperate, introgression) and 650 differently expressed genes between the two temperature treatments (25°C, 34°C). Additionally, I identify gene clusters containing a total of 985 genes that were significantly associated with response to heat stress, and one gene cluster containing a total of 52 genes that were significantly associated with LT50. Functional analysis of these differentially expressed genes and clusters indicates that precise regulation of aerobic metabolism and oxidative phosphorylation is instrumental in reducing cellular damage accrued due to the formation of reactive oxygen species (ROS) by downregulating processes that lead to ROS formation. I observe a strongly conserved heat shock response to the stressful treatment temperature amongst all genotypes, including upregulation of protective elements and some metabolic downregulation. The most prominent finding, supported by the list of genes containing polymorphisms in different allelic frequencies between temperate and introgression genotypes, was the difference in magnitude and depth of the downregulation of metabolic systems in more thermally tolerant embryos. In addition to reduction of catabolic activity, more nuanced regulation of transcriptional machinery and the formation subcellular nucleoprotein complexes appear to be plastic mechanisms contributing to the divergence in thermal tolerance between locally adapted regional genotypes.
Author: David L. Denlinger
Publisher: Cambridge University Press
ISBN: 1139485474
Category : Science
Languages : en
Pages :
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Book Description
Low temperature is a major environmental constraint impacting the geographic distribution and seasonal activity patterns of insects. Written for academic researchers in environmental physiology and entomology, this book explores the physiological and molecular mechanisms that enable insects to cope with a cold environment and places these findings into an evolutionary and ecological context. An introductory chapter provides a primer on insect cold tolerance and subsequent chapters in the first section discuss the organismal, cellular and molecular responses that allow insects to survive in the cold despite their, at best, limited ability to regulate their own body temperature. The second section, highlighting the evolutionary and macrophysiological responses to low temperature, is especially relevant for understanding the impact of global climate change on insect systems. A final section translates the knowledge gained from the rest of the book into practical applications including cryopreservation and the augmentation of pest management strategies.
Author: Pierre Capy
Publisher: Springer
ISBN: 9789401037556
Category : Science
Languages : en
Pages : 293
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Book Description
Comparison of closely related species is a powerful D. melanogaster. In D. melanogaster, microsatel approach to understanding the changes that have oc lites reveal that West African popUlations are more curred since their divergence from a common ancestor. closely related to non-African populations than to The sibling species Drosophila melanogaster and D. East African popUlations. East African populations are simulans are probably the species pair for which the more variable than West African or non-African popu most genetic data are available. A workshop held at lations, suggesting that East African populations may 1 Gif/Yvette in January 2002 reviewed and discussed more closely reflect African ancestral variability. comparisons between these species, from their ecol Ecophysiology, popUlation dynamics and popula tion structure are also important to understanding the ogy and biogeography to their behavior and DNA evolution of the two species. Genetic diversity (8) polymorphism. is higher in D. simulans (S. Mousset and R. Singh).
Author:
Publisher: Elsevier
ISBN: 008047117X
Category : Science
Languages : en
Pages : 259
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Book Description
Advances in Insect Physiology publishes eclectic volumes containing important, comprehensive and in-depth reviews on all aspects of insect physiology. It is an essential reference source for invertebrate physiologists and neurobiologists, entomologists, zoologists and insect biochemists. First published in 1963, the serial is now edited by Steve Simpson (Oxford University, UK). - More than 300 pages with contributions from the leading researchers in entomology - Over 40 figures and illustrations combined - Includes an in-depth review of the genetics of the honey bee - Discusses the physiological diversity in insects
Author: V. Loeschcke
Publisher: Birkhäuser
ISBN: 3034885105
Category : Science
Languages : en
Pages : 427
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Book Description
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: Rodney Mauricio
Publisher: Springer Science & Business Media
ISBN: 1402038364
Category : Science
Languages : en
Pages : 207
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Book Description
An enduring controversy in evolutionary biology is the genetic basis of adaptation. Darwin emphasized "many slight differences" as the ultimate source of variation to be acted upon by natural selection. In the early 1900’s, this view was opposed by "Mendelian geneticists", who emphasized the importance of "macromutations" in evolution. The Modern Synthesis resolved this controversy, concluding that mutations in genes of very small effect were responsible for adaptive evolution. A decade ago, Allen Orr and Jerry Coyne reexamined the evidence for this neo-Darwinian view and found that both the theoretical and empirical basis for it were weak. Orr and Coyne encouraged evolutionary biologists to reexamine this neglected question: what is the genetic basis of adaptive evolution? In this volume, a new generation of biologists have taken up this challenge. Using advances in both molecular genetic and statistical techniques, evolutionary geneticists have made considerable progress in this emerging field. In this volume, a diversity of examples from plant and animal studies provides valuable information for those interested in the genetics and evolution of complex traits.
