Long-term animal research in genetic improvement of livestock and poultry

1996 ◽  
Vol 76 (4) ◽  
pp. 581-585
Author(s):  
E. B. Burnside
Keyword(s):  
Animal Species ◽  
Genetic Variance ◽  
Genetic Selection ◽  
Selection Response ◽  
Animal Experimentation ◽  
Private Industry ◽  
Animal Products ◽  
Selection Experiments ◽  
Long Term Studies

In animal experimentation, long-term studies have contributed substantially to our knowledge of genetics in particular, and of nutrition, physiology, and reproduction, to lesser extents. Long-term genetic selection experiments have yielded information on selection limits, dissipation of genetic variance over time, and created unique lines which may be utilized as consumer demands shift. Costs of long-term experimentation are not inordinately high in comparison to other experimentation, if economic animal species are used and returns from animal products are recovered to help finance the experiment. Government finance is, however, required for long-term experimentation, as private industry has little motivation for this work. The paper outlines recent significant contributions of long-term experimentation, and provides guidelines for planning experiments. Key words: Selection response, animal genetics, long-term experimentation, experimental design

scholarly journals Selection Response in Finite Populations

Genetics ◽  
1996 ◽  
Vol 144 (4) ◽  
pp. 1961-1974 ◽  
Author(s):  
Ming Wei ◽  
Armando Caballero ◽  
William G Hill
Keyword(s):  
Linkage Disequilibrium ◽  
Inbreeding Depression ◽  
Genetic Variance ◽  
Relative Rate ◽  
Selection Response ◽  
Rate Of Change ◽  
Effective Population ◽  
Short Term ◽  
Model Account

Formulae were derived to predict genetic response under various selection schemes assuming an infinitesimal model. Account was taken of genetic drift, gametic (linkage) disequilibrium (Bulmer effect), inbreeding depression, common environmental variance, and both initial segregating variance within families (σAW02) and mutational (σM2) variance. The cumulative response to selection until generation t(CRt) can be approximated asCRt≈R0[t−β(1−σAW∞2σAW02)t24Ne]−Dt2Ne,where Ne is the effective population size, σAW∞2=NeσM2 is the genetic variance within families at the steady state (or one-half the genic variance, which is unaffected by selection), and D is the inbreeding depression per unit of inbreeding. R  0 is the selection response at generation 0 assuming preselection so that the linkage disequilibrium effect has stabilized. β is the derivative of the logarithm of the asymptotic response with respect to the logarithm of the within-family genetic variance, i.e., their relative rate of change. R  0 is the major determinant of the short term selection response, but σM2, Ne and β are also important for the long term. A selection method of high accuracy using family information gives a small Ne and will lead to a larger response in the short term and a smaller response in the long term, utilizing mutation less efficiently.

Selection Response in Natural Populations

2018 ◽  
Author(s):  
Bruce Walsh ◽  
Michael Lynch
Keyword(s):  
Natural Populations ◽  
Selection Response ◽  
Correlated Response ◽  
Sources Of Error ◽  
True Target ◽  
Change In The Mean ◽  
The Mean ◽  
Actual Target ◽  
Long Term Studies

The breeder's equation often fails when applied to natural populations. In large part, this likely occurs because the assumed trait is not the actual target of selection. A within-generation change in the mean of a suggested target trait can arise as a correlated response from selection acting elsewhere. This chapter examines sources of error in the breeder's equation and approaches that attempt to determine if an assumed trait is actually the true target of selection. It also reviews a number of long-term studies from natural populations and examines possible sources for the failure of most of these studies to conform to the expectations of the breeder's equation.

scholarly journals The Impact of Genomic and Traditional Selection on the Contribution of Mutational Variance to Long-Term Selection Response and Genetic Variance

Genetics ◽  
2019 ◽  
Vol 213 (2) ◽  
pp. 361-378 ◽  
Author(s):  
Herman A. Mulder ◽  
Sang Hong Lee ◽  
Sam Clark ◽  
Ben J. Hayes ◽  
Julius H. J. van der Werf
Keyword(s):  
Genetic Variance ◽  
Selection Response ◽  
Term Selection ◽  
The Impact ◽  
Mutational Variance

Testing quantitative genetic selection theory with the mouse: A review

2005 ◽  
Vol 2005 ◽  
pp. 238-238
Author(s):  
E. J. Eisen
Keyword(s):  
Genetic Selection ◽  
Selection Response ◽  
Farm Animals ◽  
Base Population ◽  
Selection Theory ◽  
Quantitative Genetic ◽  
Selection Experiments ◽  
Downward Bias ◽  
Dynamic Population ◽  
Good Agreement

The theory of quantitative genetics is used to predict certain outcomes in a dynamic population undergoing selection. The goal of this review is to demonstrate the value of the mouse as a model to test quantitative genetic selection theory.Heritablity estimates in a base population are used to predict selection response. How good is this prediction? Sheridan (1988) reported discrepancies between predicted and realized heritabilities in selection experiments with laboratory and farm animals. An updated summary of single-trait selection experiments for different traits in mice indicates good agreement between predicted and realized heritabilities (r = 0.81, P < 0.01), with no suggestion of upward or downward bias in the base estimates (Eisen, 2005).

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 SELECTION LIMIT DUE TO THE CONFLICT BETWEEN TRUNCATION AND STABILIZING SELECTION WITH MUTATION

Genetics ◽  
1986 ◽  
Vol 114 (4) ◽  
pp. 1313-1328
Author(s):  
Zhao-Bang Zeng ◽  
William G Hill
Keyword(s):  
Genetic Variation ◽  
Genetic Variance ◽  
Selection Response ◽  
Stabilizing Selection ◽  
Phenotypic Variance ◽  
Selection Differential ◽  
Term Selection ◽  
Truncation Selection ◽  
Infinite Population

ABSTRACT Long-term selection response could slow down from a decline in genetic variance or in selection differential or both. A model of conflict between truncation and stabilizing selection in infinite population size is analysed in terms of the reduction in selection differential. Under the assumption of a normal phenotypic distribution, the limit to selection is found to be a function of κ, the intensity of truncation selection, ω 2, a measure of the intensity of stabilizing selection, and σ 2, the phenotypic variance of the character. The maintenance of genetic variation at this limit is also analyzed in terms of mutation-selection balance by the use of the "House-of-cards" approximation. It is found that truncation selection can substantially reduce the equilibrium genetic variance below that when only stabilizing selection is acting, and the proportional reduction in variance is greatest when the selection is very weak. When truncation selection is strong, any further increase in the strength of selection has little further influence on the variance. It appears that this mutation-selection balance is insufficient to account for the high levels of genetic variation observed in many long-term selection experiments.

Implications of Long-Term Studies of Three Model Preschool Programs for Head Start

2008 ◽  
Author(s):  
Lawrence J. Schweinhart ◽  
Elena V. Malofeeva ◽  
Lawrence J. Schweinhart ◽  
Michelle M. Englund ◽  
Arthur J. Reynolds ◽  
...  
Keyword(s):  
Head Start ◽  
Preschool Programs ◽  
Long Term Studies

Primary varicose veins

Phlebologie ◽  
2010 ◽  
Vol 39 (03) ◽  
pp. 133-137
Author(s):  
H. Partsch
Keyword(s):  
Varicose Veins ◽  
Compression Therapy ◽  
Daily Practice ◽  
Clinical Severity ◽  
Compression Stockings ◽  
Primary Varicose Veins ◽  
The Cost ◽  
Convincing Data ◽  
Long Term Studies

SummaryBackground: Compression stockings are widely used in patients with varicose veins. Methods: Based on published literature three main points are discussed: 1. the rationale of compression therapy in primary varicose veins, 2. the prescription of compression stockings in daily practice, 3. studies required in the future. Results: The main objective of prescribing compression stockings for patients with varicose veins is to improve subjective leg complaints and to prevent swelling after sitting and standing. No convincing data are available concerning prevention of progression or of complications. In daily practice varicose veins are the most common indication to prescribe compression stockings. The compliance depends on the severity of the disorder and is rather poor in less severe stages. Long-term studies are needed to proof the cost-effectiveness of compression stockings concerning subjective symptoms and objective signs of varicose veins adjusted to their clinical severity. Conclusion: Compression stockings in primary varicose veins are able to improve leg complaints and to prevent swelling.

Diatoms and aquatic palynomorphs in the sediments of the Eurasian Arctic seas and their significance for paleooceanological investigations in the Arctic

2019 ◽  
pp. 246-251
Author(s):  
Yelena I. Polyakova ◽  
Yekaterina I. Novichkova ◽  
Tatiana S. Klyuvitkina ◽  
Elizaveta A. Agafonova ◽  
Irina M. Kryukova
Keyword(s):  
Bering Sea ◽  
Surface Sediments ◽  
Sea Water ◽  
The Arctic ◽  
Marginal Filter ◽  
Arctic Seas ◽  
Hydrological Parameters ◽  
The Arctic Ocean ◽  
Long Term Studies

Presented the results of long-term studies of diatoms and aquatic palynomorphs in surface sediments of the Arctic seas and the possibility of their use for the reconstructions of paleocirculation water masses, advection of Atlantic and Bering sea water into the Arctic ocean, changes in the river runoff to the seas, sedimentary processes in the marginal filter of the largest rivers, seasonal sea ice cover and other hydrological parameters.

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