Author: Donald V. Griffin
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Languages : en
Pages :
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For both experiments, I use fly populations established by Houle et al. that had undergone thirty generations of artificial selection on an index of wing shape. The line-cross analysis suggests that the two lines selected to increase or decrease the wing shape index score had decanalized genetic architectures with respect to their second generation hybrids. This is consistent with the idea that wing shape evolutionary stasis is due, in part, to low evolvability of the trait. The chromosome substitution experiment was hampered by the extinction of over fifty percent of the substitution lines in the experimental design, and so the results had little power to estimate the genetic architecture of the trait. However, the best estimate of the analysis suggests a negative directional epistasis, which is also consistent with the hypothesis that the wings are canalized.
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Languages : en
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Building on quantitative genetic analysis in fruitflies I chose to investigate the molecular genetic underpinnings of natural variation in wing shape. Shape is a complex trait demanding a multidimensional description and was adequately portrayed and quantified with the tools of morphometrics. The results demonstrate uncoupling of size and shape. Shape shows strong degree of integration over the structure, disputing hypothesis of the wing as comprised of independent modules laid down by compartmentalization. However, distinctly local shape effects are also observed in genetic correlations, complementation and association tests, arguing for a continuous distribution along an axis of integration and modularity. The identification of quantitative trait nucleotides within a QTL was pursed in a two step scheme. First I tested a set of candidate loci, implicated by QTL experiments and/or developmental roles, for contribution to wing shape. The results are consistent with segregating variation of loci in the vein-determining pathways, hedgehog (hh), decapentaplegic (dpp) and Epidermal growth factor Receptor (EGFR), impacting shape. The second step involved fine-scale mapping, by testing for associations between EGFR and wing shape in two geographic populations of D. melanogaster. The genotyping was done by sequencing 10.9 kb of the locus from 209 lines demonstrating a mostly neutral locus, possibly experiencing purifying selection. One of two alternate 5'-exons may be evolving more rapidly by positive directional selection. Linkage disequilibrium decays rapidly within EGFR increasing the resolution of association mapping. Association tests identified one site (C31365T) with sex dependent effects on wing size, significant after Bonferroni correction. Seven more sites are weakly suggested. The highest of those (C30200T) disrupts a putative GAGA factor binding element and has replicable effects on crossvein placement in three study designs. The work suggests naturally occurrin.
Author: Arnar Pálsson
Publisher:
ISBN:
Category :
Languages : en
Pages : 215
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Keywords: relative warp analysis, quantitative trait loci, linkage disequilibrium mapping, microsatellite, evolution.
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: Anne Charmantier
Publisher: OUP Oxford
ISBN: 0191655961
Category : Science
Languages : en
Pages : 288
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Book Description
Although the field of quantitative genetics - the study of the genetic basis of variation in quantitative characteristics such as body size, or reproductive success - is almost 100 years old, its application to the study of evolutionary processes in wild populations has expanded greatly over the last few decades. During this time, the use of 'wild quantitative genetics' has provided insights into a range of important questions in evolutionary ecology, ranging from studies conducting research in well-established fields such as life-history theory, behavioural ecology and sexual selection, to others addressing relatively new issues such as populations' responses to climate change or the process of senescence in natural environments. Across these fields, there is increasing appreciation of the need to quantify the genetic - rather than just the phenotypic - basis and diversity of key traits, the genetic basis of the associations between traits, and the interaction between these genetic effects and the environment. This research activity has been fuelled by methodological advances in both molecular genetics and statistics, as well as by exciting results emerging from laboratory studies of evolutionary quantitative genetics, and the increasing availability of suitable long-term datasets collected in natural populations, especially in animals. Quantitative Genetics in the Wild is the first book to synthesize the current level of knowledge in this exciting and rapidly-expanding area. This comprehensive volume also offers exciting perspectives for future studies in emerging areas, including the application of quantitative genetics to plants or arthropods, unraveling the molecular basis of variation in quantitative traits, or estimating non-additive genetic variance. Since this book deals with many fundamental questions in evolutionary ecology, it should be of interest to graduate, post-graduate students, and academics from a wide array of fields such as animal behaviour, ecology, evolution, and genetics.
Author: Desiree Michelle Breanna Unselt
Publisher:
ISBN:
Category :
Languages : en
Pages : 286
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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.
Author: Martijn Zoodsma
Publisher:
ISBN:
Category :
Languages : en
Pages : 23
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Author: Rama S. Singh
Publisher: Cambridge University Press
ISBN: 1139449540
Category : Science
Languages : en
Pages : 492
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Book Description
This 2004 collection of essays deals with the foundation and historical development of population biology and its relationship to population genetics and population ecology on the one hand and to the rapidly growing fields of molecular quantitative genetics, genomics and bioinformatics on the other. Such an interdisciplinary treatment of population biology has never been attempted before. The volume is set in a historical context, but it has an up-to-date coverage of material in various related fields. The areas covered are the foundation of population biology, life history evolution and demography, density and frequency dependent selection, recent advances in quantitative genetics and bioinformatics, evolutionary case history of model organisms focusing on polymorphisms and selection, mating system evolution and evolution in the hybrid zones, and applied population biology including conservation, infectious diseases and human diversity. This is the third of three volumes published in honour of Richard Lewontin.
Author: Susan Tracy Harbison
Publisher:
ISBN:
Category :
Languages : en
Pages : 6113
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Keywords: deficiency complementation mapping, microarray, QTL mapping.
