scholarly journals Fluctuating environments and the role of mutation in maintaining quantitative genetic variation

2002 ◽  
Vol 80 (1) ◽  
pp. 31-46 ◽  
Author(s):  
REINHARD BÜRGER ◽  
ALEXANDER GIMELFARB
Keyword(s):  
Genetic Variation ◽  
Genetic Parameters ◽  
Numerical Approach ◽  
Recurrent Mutation ◽  
Fluctuating Selection ◽  
Quantitative Genetic ◽  
Wide Range ◽  
Fluctuating Environments ◽  
Ecological Parameters

We study a class of genetic models in which a quantitative trait determined by several additive loci is subject to temporally fluctuating selection. Selection on the trait is assumed to be stabilizing but with an optimum that varies periodically and might be perturbed stochastically. The population mates at random, is infinitely large and has discrete generations. We pursue a statistical and numerical approach, covering a wide range of ecological and genetic parameters, to determine the potential of fluctuating environments to maintain quantitative genetic variation. Whereas, in contrast to some recent claims, this potential seems to be rather limited in the absence of recurrent mutation, fluctuating environments might, in combination with it, often generate high levels of additive genetic variation. We investigate how the genetic variation maintained depends on the ecological parameters and on the underlying genetics.

Maintenance of Quantitative Genetic Variation

2018 ◽  
Author(s):  
Bruce Walsh ◽  
Michael Lynch
Keyword(s):  
Genetic Variation ◽  
Quantitative Genetics ◽  
Stabilizing Selection ◽  
Quantitative Genetic ◽  
Wide Range

One of the major unresolved issues in quantitative genetics is what accounts for the amount of standing genetic variation in traits. A wide range of models, all reviewed in this chapter, have been proposed, but none fit the data, either giving too much variation or too little apparent stabilizing selection.

scholarly journals What can genetic variation tell us about the evolution of senescence?

2009 ◽  
Vol 276 (1665) ◽  
pp. 2271-2278 ◽  
Author(s):  
Jacob A. Moorad ◽  
Daniel E.L. Promislow
Keyword(s):  
Genetic Variation ◽  
Variance Components ◽  
Genetic Parameters ◽  
Genetic Variance ◽  
Mutation Accumulation ◽  
Antagonistic Pleiotropy ◽  
Age Classes ◽  
Dominance Variance ◽  
Quantitative Genetic ◽  
Genetic Techniques

Quantitative genetic approaches have been developed that allow researchers to determine which of two mechanisms, mutation accumulation (MA) or antagonistic pleiotropy (AP), best explain observed variation in patterns of senescence using classical quantitative genetic techniques. These include the creation of mutation accumulation lines, artificial selection experiments and the partitioning of genetic variances across age classes. This last strategy has received the lion's share of empirical attention. Models predict that inbreeding depression (ID), dominance variance and the variance among inbred line means will all increase with age under MA but not under those forms of AP that generate marginal overdominance. Here, we show that these measures are not, in fact, diagnostic of MA versus AP. In particular, the assumptions about the value of genetic parameters in existing AP models may be rather narrow, and often violated in reality. We argue that whenever ageing-related AP loci contribute to segregating genetic variation, polymorphism at these loci will be enhanced by genetic effects that will also cause ID and dominance variance to increase with age, effects also expected under the MA model of senescence. We suggest that the tests that seek to identify the relative contributions of AP and MA to the evolution of ageing by partitioning genetic variance components are likely to be too conservative to be of general value.

scholarly journals Differences in Steap3 expression are a mechanism of genetic variation of RBC storage and oxidative damage in mice

2019 ◽  
Vol 3 (15) ◽  
pp. 2272-2285 ◽  
Author(s):  
Heather L. Howie ◽  
Ariel M. Hay ◽  
Karen de Wolski ◽  
Hayley Waterman ◽  
Jenna Lebedev ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Oxidative Damage ◽  
Cellular Membrane ◽  
Biological Properties ◽  
Substantial Effect ◽  
The Body ◽  
Redox Biology ◽  
Wide Range ◽  
Different Strains

Abstract Red blood cells (RBCs) are the most numerous cell type in the body and serve a vital purpose of delivering oxygen to essentially all tissues. In addition to the central role of RBCs in health and disease, RBC storage is a requirement for the >90 million units of RBC transfusions given to millions of recipients each year, worldwide. It is well known that there is genetic donor-to-donor variability in how human RBCs store, rendering blood a nonstandardized therapeutic with a wide range of biological properties from unit to unit, by the time it is transfused. As with humans, genetic variation exists in how murine RBCs, from different strains of mice, store and perform after transfusion. The genetic mechanisms for variation, in humans and mice, both remain obscure. Combining advanced metabolomics, genetics, and molecular and cellular biology approaches, we identify genetic variation in six-transmembrane epithelial antigen of prostate 3 (Steap3) expression as a critical and previously unrecognized mechanism of oxidative damage of RBCs during storage. Increased levels of Steap3 result in degradation of cellular membrane through lipid peroxidation, leading to failure of RBC homeostasis and hemolysis/clearance of RBCs. This article is the first report of a role of Steap3 in mature RBCs; it defines a new mechanism of redox biology in RBCs with a substantial effect upon RBC function and provides a novel mechanistic determinant of genetic variation of RBC storage.

scholarly journals MCHM acts as a hydrotrope, altering the balance of metals in yeast

2019 ◽  
Author(s):  
Amaury Pupo ◽  
Michael C. Ayers ◽  
Zachary N. Sherman ◽  
Rachel J. Vance ◽  
Jonathan R. Cumming ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Protein Interactions ◽  
Industrial Chemicals ◽  
Metal Transporters ◽  
Coal Cleaning ◽  
Wide Range ◽  
Molecular Effects ◽  
Response Expression

AbstractWhile drugs and other industrial chemicals are routinely studied to assess risks, many widely-used chemicals have not been thoroughly evaluated. One such chemical, 4-methylcyclohexane methanol (MCHM), is an industrial coal-cleaning chemical that contaminated the drinking-water supply in Charleston, WV, USA in 2014. While a wide range of ailments was reported following the spill, little is known about the molecular effects of MCHM exposure. We used the yeast model to explore the impacts of MCHM on cellular function. Exposure to MCHM dramatically altered the yeast transcriptome and the balance of metals in yeast. Underlying genetic variation in the response to MCHM and transcriptomics and mutant analysis uncovered the role of the metal transporters, Arn2 and Yke4, to MCHM response. Expression of Arn2, involved in iron uptake, was lower in MCHM-tolerant yeast and loss of Arn2 further increased MCHM tolerance. Genetic variation within Yke4, an ER zinc transporter, also mediated response to MCHM and loss of Yke4 decreased MCHM tolerance. The addition of zinc to MCHM-sensitive yeast rescued growth inhibition. In vitro assays demonstrated that MCHM acted as a hydrotrope and prevented protein-interactions, while zinc-induced the aggregation of proteins. We hypothesized that MCHM altered the structures of extracellular domains of proteins, and the addition of zinc stabilized the structure to maintain metal homeostasis in yeast exposed to MCHM.

scholarly journals Different mechanisms drive the maintenance of polymorphism at loci subject to strong versus weak fluctuating selection

2017 ◽  
Author(s):  
Jason Bertram ◽  
Joanna Masel
Keyword(s):  
Genetic Variation ◽  
Time Reversal ◽  
The Other ◽  
Simplified Model ◽  
Fluctuating Selection ◽  
Stabilizing Effect ◽  
Balance Polymorphism ◽  
Genetic Mechanisms ◽  
Over Time

AbstractThe long-running debate about the role of selection in maintaining genetic variation has been given new impetus by the discovery of hundreds of seasonally oscillating polymorphisms in wild Drosophila, possibly stabilized by an alternating summer-winter selection regime. Historically there has been skepticism about the potential of temporal variation to balance polymorphism, because selection must be strong to have a meaningful stabilizing effect — unless dominance also varies over time (“reversal of dominance”). Here we develop a simplified model of seasonally variable selection that simultaneously incorporates four different stabilizing mechanisms, including two genetic mechanisms (“cumulative overdominance” and reversal of dominance), as well as ecological “storage” (“protection from selection” and boom-bust demography). We use our model to compare the stabilizing effects of these mechanisms. Although reversal of dominance has by far the greatest stabilizing effect, we argue that the three other mechanisms could also stabilize polymorphism under plausible conditions, particularly when all three are present. With many loci subject to diminishing returns epistasis, reversal of dominance stabilizes many alleles of small effect. This makes the combination of the other three mechanisms, which are incapable of stabilizing small effect alleles, a better candidate for stabilizing the detectable frequency oscillations of large effect alleles.

The Problem of Identifying and Modeling the Relationship between Monetary Factor and Inflation in the Russian Economy

2008 ◽  
pp. 61-76
Author(s):  
A. Porshakov ◽  
A. Ponomarenko
Keyword(s):  
Money Supply ◽  
Money Demand ◽  
Russian Economy ◽  
Long Run ◽  
Complex Approach ◽  
Wide Range ◽  
Long Time ◽  
The Relationship ◽  
Supply Side Factors

The role of monetary factor in generating inflationary processes in Russia has stimulated various debates in social and scientific circles for a relatively long time. The authors show that identification of the specificity of relationship between money and inflation requires a complex approach based on statistical modeling and involving a wide range of indicators relevant for the price changes in the economy. As a result a model of inflation for Russia implying the decomposition of inflation dynamics into demand-side and supply-side factors is suggested. The main conclusion drawn is that during the recent years the volume of inflationary pressures in the Russian economy has been determined by the deviation of money supply from money demand, rather than by money supply alone. At the same time, monetary factor has a long-run spread over time impact on inflation.

Introduction: Emotion, History and the Arts

2018 ◽  
Vol 7 (2) ◽  
pp. 117-128 ◽  
Author(s):  
Erin Sullivan ◽  
Marie Louise Herzfeld-Schild
Keyword(s):  
Historical Change ◽  
Carson Mccullers ◽  
Emotional Life ◽  
Review Section ◽  
The Arts ◽  
Wide Range ◽  
War Correspondents ◽  
History Of ◽  
Johan Huizinga

This introduction surveys the rise of the history of emotions as a field and the role of the arts in such developments. Reflecting on the foundational role of the arts in the early emotion-oriented histories of Johan Huizinga and Jacob Burkhardt, as well as the concerns about methodological impressionism that have sometimes arisen in response to such studies, the introduction considers how intensive engagements with the arts can open up new insights into past emotions while still being historically and theoretically rigorous. Drawing on a wide range of emotionally charged art works from different times and places—including the novels of Carson McCullers and Harriet Beecher-Stowe, the private poetry of neo-Confucian Chinese civil servants, the photojournalism of twentieth-century war correspondents, and music from Igor Stravinsky to the Beatles—the introduction proposes five ways in which art in all its forms contributes to emotional life and consequently to emotional histories: first, by incubating deep emotional experiences that contribute to formations of identity; second, by acting as a place for the expression of private or deviant emotions; third, by functioning as a barometer of wider cultural and attitudinal change; fourth, by serving as an engine of momentous historical change; and fifth, by working as a tool for emotional connection across communities, both within specific time periods but also across them. The introduction finishes by outlining how the special issue's five articles and review section address each of these categories, while also illustrating new methodological possibilities for the field.

Short Films from a Small Nation

2018 ◽  
Author(s):  
C. Claire Thomson
Keyword(s):  
Public Information ◽  
Industrial Process ◽  
Actor Network Theory ◽  
Documentary Films ◽  
Wide Range ◽  
Short Films ◽  
Post War ◽  
The 1960S ◽  
Art And Architecture

The first book-length study in English of a national corpus of state-sponsored informational film, this book traces how Danish shorts on topics including social welfare, industry, art and architecture were commissioned, funded, produced and reviewed from the inter-war period to the 1960s. For three decades, state-sponsored short filmmaking educated Danish citizens, promoted Denmark to the world, and shaped the careers of renowned directors like Carl Th. Dreyer. Examining the life cycle of a representative selection of films, and discussing their preservation and mediation in the digital age, this book presents a detailed case study of how informational cinema is shaped by, and indeed shapes, its cultural, political and technological contexts.The book combines close textual analysis of a broad range of films with detailed accounts of their commissioning, production, distribution and reception in Denmark and abroad, drawing on Actor-Network Theory to emphasise the role of a wide range of entities in these processes. It considers a broad range of genres and sub-genres, including industrial process films, public information films, art films, the city symphony, the essay film, and many more. It also maps international networks of informational and documentary films in the post-war period, and explores the role of informational film in Danish cultural and political history.

Quantitative and Qualitative Methods of Studying the Processes of Socialization of a Modern Teenager

2020 ◽  
pp. 102-109
Author(s):  
Svetlana Alekseevna Raschetina ◽  
Keyword(s):  
Research Methods ◽  
Interpersonal Relations ◽  
Internet Communication ◽  
Socialization Process ◽  
Wide Range ◽  
The Family ◽  
Modern Family ◽  
Making Friends ◽  
Main Support

Relevance and problem statement. Modern unstable society is characterized by narrowing the boundaries of controlled socialization and expanding the boundaries of spontaneous socialization of a teenager based on his immersion in the question arises about the importance of the family in the process of socialization of a teenager in the conditions of expanding the space of socialization. There is a need to study the role of the family in this process, to search, develop and test research methods that allow us to reveal the phenomenon of socialization from the side of its value characteristics. The purpose and methodology of the study: to identify the possibilities of a systematic and anthropological methodology for studying the role of the family in the process of socialization of adolescents in modern conditions, testing research methods: photo research on the topic “Ego – I” (author of the German sociologist H. Abels), profile update reflexive processes (by S. A. Raschetina). Materials and results of the study. The study showed that for all the problems that exist in the family of the perestroika era and in the modern family, it acts for a teenager as a value and the first (main) support in the processes of socialization. The positions well known in psychology about the importance of interpersonal relations in adolescence for the formation of attitudes towards oneself as the basis of socialization are confirmed. Today, the frontiers of making friends have expanded enormously on the basis of Internet communication. The types of activities of interest to a teenager (traditional and new ones related to digitalization) are the third pillar of socialization. Conclusion. The “Ego – I” method of photo research has a wide range of possibilities for quantitative and qualitative analysis of the socialization process to identify the value Pillars of this process.

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