scholarly journals The rate of polygenic mutation

1988 ◽  
Vol 51 (2) ◽  
pp. 137-148 ◽  
Author(s):  
Michael Lynch
Keyword(s):  
Genetic Variance ◽  
Phenotypic Evolution ◽  
Neutral Model ◽  
Base Population ◽  
Crop Species ◽  
Environmental Variance ◽  
Quantitative Estimates ◽  
Practical Implications ◽  
Term Response

SummaryBy application of the neutral model of phenotypic evolution, quantitative estimates of the rate of input of genetic variance by polygenic mutation can be extracted from divergence experiments as well as from the response of an inbred base population to selection. The analytical methods are illustrated through a survey of data on a diversity of organisms including Drosophila, Tribolium, mice, and several crop species. The mutational rate of introduction of genetic variance (Vm) scaled by the environmental variance (VE) is shown to vary between populations, species, and characters with a range of approximately 10−4 to 5 × 10−2. Vm/VE for Drosophila viability is somewhat below this range, while hybrid dysgenesis may temporarily inflate Vm/VE beyond 10−1. Potential sources of bias and error in the estimation of Vm are discussed, as are the practical implications of the observed limits to Vm/VE for projecting the long-term response to selection and for testing adaptational hypotheses.

Genetic parameters for lean mass in long term selection with mice

1991 ◽  
Vol 1991 ◽  
pp. 12-12
Author(s):  
B.K. Beniwal ◽  
R. Thompson ◽  
W.G. Hill
Keyword(s):  
Animal Model ◽  
Lean Mass ◽  
Genetic Variance ◽  
Laboratory Animals ◽  
Relationship Matrix ◽  
Reproduction Rate ◽  
Base Population ◽  
Selected Lines ◽  
Term Selection

Long term selection experiments with laboratory animals can provide an excellent opportunity to examine the assumptions underlying the predictions in animal breeding because of their short generation interval and high reproduction rate. The infinitesimal model of many genes each with small effect is often assumed for the analysis of economic traits in livestock species which have been selected by breeders for different objectives. Under such assumptions the genetic variance is expected to be reduced in a predictable way due to selection (Bulmer effect) and inbreeding in a selection experiment. The Animal Model with a complete relationship matrix back to the base population accounts for these reductions in genetic variance due to inbreeding and selection and thus provides an unbiased estimate of genetic variance in the base population (Sorensen and Kennedy, 1984). Lean mass in selected lines of mice was analysed using the individual animal model, to test if the infinitesimal model assumptions hold in the selected lines for this trait

USING A HAND-TAP RESPONSE WITH A VIBRATION MICROSWITCH WITH STUDENTS WITH MULTIPLE DISABILITIES

2002 ◽  
Vol 30 (2) ◽  
pp. 237-241 ◽  
Author(s):  
Giulio E. Lancioni ◽  
Nirbhay N. Singh ◽  
Mark F. O'Reilly ◽  
Doretta Oliva
Keyword(s):  
Multiple Disabilities ◽  
Practical Implications ◽  
Term Response

Selecting a convenient response, and a microswitch suitable to it, is critical to successfully introduce students with multiple disabilities to a microswitch-aided programme. This study evaluated the use of a hand-tap response with a vibration microswitch with two students. Both students increased the frequency of the hand-tap response during treatment and maintained such an increase at 3-month follow-up. Procedural issues, practical implications of the findings, and measures for promoting long-term response maintenance/extensions were discussed.

Using Simple Hand-Movement Responses with Optic Microswitches with Two Persons with Multiple Disabilities

2002 ◽  
Vol 27 (4) ◽  
pp. 276-279 ◽  
Author(s):  
Giulio E. Lancioni ◽  
Nirbhay N. Singh ◽  
Mark F. O'Reilly ◽  
Doretta Oliva ◽  
Simona Baccani ◽  
...  
Keyword(s):  
Hand Movement ◽  
Multiple Disabilities ◽  
Practical Implications ◽  
Term Response

In this study, we assessed whether a program involving simple hand-movement responses combined with optic microswitches and followed by preferred stimuli would be successful (i.e., increasing responding and stimulation) with two persons with multiple disabilities. Data showed that both persons reached fairly high levels of responding during intervention and retained their achievement through subsequent maintenance periods of 3 or 6 months. Procedural issues, practical implications of the findings, and measures for promoting long-term response maintenance–extensions were discussed.

Long-term Response: 1. Deterministic Aspects

2018 ◽  
Author(s):  
Bruce Walsh ◽  
Michael Lynch
Keyword(s):  
Genetic Variance ◽  
Major Gene ◽  
Additive Genetic Variance ◽  
Large Population ◽  
New Mutation ◽  
Actual Nature ◽  
Selection Experiments ◽  
Selection Limit ◽  
Term Response

In a large population in the absence of new mutation, selection is expected to eventually drive all of the additive-genetic variance in a trait toward zero, resulting in a selection limit. This chapter examines the underlying population-genetics of such a limit, how it is estimated, and reviews the actual nature of limits observed in artificial selection experiments. It also examines the conditions under which a major gene is more important than polygenic response.

scholarly journals The long-term effects of genomic selection: Response to selection, additive genetic variance and genetic architecture

2021 ◽  
Author(s):  
Yvonne C.J. Wientjes ◽  
Piter Bijma ◽  
Mario P.L. Calus ◽  
Bas J. Zwaan ◽  
Zulma G. Vitezica ◽  
...  
Keyword(s):  
Genomic Selection ◽  
Genetic Architecture ◽  
Genetic Variance ◽  
Phenotypic Selection ◽  
Allele Frequencies ◽  
Additive Effects ◽  
Long Term Effects ◽  
Pedigree Selection ◽  
Term Response

ABSTRACTGenomic selection has revolutionized genetic improvement in animals and plants, but little is known of its long term effects. Here we investigate the long-term effects of genomic selection on the change in the genetic architecture of traits over generations. We defined the genetic architecture as the subset, allele frequencies and statistical additive effects of causal loci. We simulated a livestock population under 50 generations of phenotypic, pedigree, or genomic selection for a single trait, controlled by either only additive, additive and dominance, or additive, dominance and epistatic effects. The simulated epistasis was based on yeast data. The observed change in genetic architecture over generations was similar for genomic and pedigree selection, and slightly smaller for phenotypic selection. Short-term response was highest with genomic selection, while long-term response was highest with phenotypic selection, especially when non-additive effects were present. This was mainly because the loss in genetic variance and in segregating loci was much greater with genomic selection. Compared to pedigree selection, genomic selection lost a similar amount of the genetic variance but maintained more segregating loci, which on average had lower minor allele frequencies. For all selection methods, the presence of epistasis limited the changes in allele frequency and the fixation of causal loci, and substantially changed the statistical additive effects over generations. Our results show that non-additive effects can have a substantial impact on the change in genetic architecture. Therefore, non-additive effects can substantially impact the accuracy and future genetic gain of genomic selection.

From Help Giving to Helping Relations

2018 ◽  
pp. 464-488
Author(s):  
Arie Nadler
Keyword(s):  
Well Being ◽  
Psychological Research ◽  
Psychological Needs ◽  
Social Psychological ◽  
Significant Relationships ◽  
Long Run ◽  
Help Giving ◽  
Social Psychological Research ◽  
Practical Implications

This chapter reviews social psychological research on help giving and helping relations from the 1950s until today. The first section considers the conditions under which people are likely to help others, personality dispositions that characterize helpful individuals, and motivational and attributional antecedents of helpfulness. The second section looks at long-term consequences of help and examines help in the context of enduring and emotionally significant relationships. Research has shown that in the long run help can increase psychological and physical well-being for helpers but discourage self-reliance for recipients. The third section analyzes helping from intra- and intergroup perspectives, considering how its provision can contribute to helpers’ reputations within a group or promote the positive social identity of in-groups relative to out-groups. Help is thus conceptualized as a negotiation between the fundamental psychological needs for belongingness and independence. Theoretical and practical implications are discussed.

scholarly journals Adaptation of flocculent anammox culture to low temperature by cold shock: long-term response of microbial population

2021 ◽  
pp. 1-19
Author(s):  
Vojtech Kouba ◽  
Juan Camilo Gerlein ◽  
Andrea Benakova ◽  
Marco Antonio Lopez Marin ◽  
Eva Rysava ◽  
...  
Keyword(s):  
Low Temperature ◽  
Cold Shock ◽  
Microbial Population ◽  
Term Response

scholarly journals Evolutionary Stability for Interactions among Kin under Quantitative Inheritance.

Genetics ◽  
1989 ◽  
Vol 121 (4) ◽  
pp. 877-889
Author(s):  
A B Harper
Keyword(s):  
Inclusive Fitness ◽  
Fitness Function ◽  
Quantitative Inheritance ◽  
Evolutionarily Stable Strategies ◽  
Environmental Variance ◽  
Pairwise Interactions ◽  
Simplifying Assumptions ◽  
Multilocus Model ◽  
Evolutionarily Stable

Abstract The theory of evolutionarily stable strategies (ESS) predicts the long-term evolutionary outcome of frequency-dependent selection by making a number of simplifying assumptions about the genetic basis of inheritance. I use a symmetrized multilocus model of quantitative inheritance without mutation to analyze the results of interactions between pairs of related individuals and compare the equilibria to those found by ESS analysis. It is assumed that the fitness changes due to interactions can be approximated by the exponential of a quadratic surface. The major results are the following. (1) The evolutionarily stable phenotypes found by ESS analysis are always equilibria of the model studied here. (2) When relatives interact, one of the two conditions for stability of equilibria differs between the two models; this can be accounted for by positing that the inclusive fitness function for quantitative characters is slightly different from the inclusive fitness function for characters determined by a single locus. (3) The inclusion of environmental variance will in general change the equilibrium phenotype, but the equilibria of ESS analysis are changed to the same extent by environmental variance. (4) A class of genetically polymorphic equilibria occur, which in the present model are always unstable. These results expand the range of conditions under which one can validly predict the evolution of pairwise interactions using ESS analysis.

scholarly journals Characterization of Deleterious Mutations in Outcrossing Populations

Genetics ◽  
1998 ◽  
Vol 150 (2) ◽  
pp. 945-956 ◽  
Author(s):  
Hong-Wen Deng
Keyword(s):  
Genetic Variation ◽  
Genetic Variance ◽  
Estimation Bias ◽  
Deleterious Mutations ◽  
Environmental Variance ◽  
Higher Power ◽  
Sib Mating ◽  
The Mean ◽  
Simulation Results

Abstract Deng and Lynch recently proposed estimating the rate and effects of deleterious genomic mutations from changes in the mean and genetic variance of fitness upon selfing/outcrossing in outcrossing/highly selfing populations. The utility of our original estimation approach is limited in outcrossing populations, since selfing may not always be feasible. Here we extend the approach to any form of inbreeding in outcrossing populations. By simulations, the statistical properties of the estimation under a common form of inbreeding (sib mating) are investigated under a range of biologically plausible situations. The efficiencies of different degrees of inbreeding and two different experimental designs of estimation are also investigated. We found that estimation using the total genetic variation in the inbred generation is generally more efficient than employing the genetic variation among the mean of inbred families, and that higher degree of inbreeding employed in experiments yields higher power for estimation. The simulation results of the magnitude and direction of estimation bias under variable or epistatic mutation effects may provide a basis for accurate inferences of deleterious mutations. Simulations accounting for environmental variance of fitness suggest that, under full-sib mating, our extension can achieve reasonably well an estimation with sample sizes of only ∼2000-3000.

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