Choosing trial sites to maximize selection response for grain yield in spring wheat

1981 ◽  
Vol 32 (3) ◽  
pp. 411 ◽  
Author(s):  
DG Pederson ◽  
AJ Rathjen
Keyword(s):  
South Australia ◽  
Selection Response ◽  
Wheat Breeding ◽  
Correlated Response ◽  
Response To Selection ◽  
Selection Scheme ◽  
Experiment Station ◽  
Optimum Selection ◽  
Coefficients Of Variation ◽  
Selection Of

Nine sites used in a wheat breeding programme in South Australia were investigated. Of the six major sites, four occupy farmers' fields and two are located on experiment stations. The data analysed comprised grain yields of 31 genotypes grown in 31 trials over a 5-year period. Relative to that grown at non-station sites, wheat grown at the experiment-station sites generally had higher mean yields, higher coefficients of variation, and lower heritabilities. Data from a set of independently conducted trials were used to estimate the true yields of the 31 genotypes. A heritability of the correlated response to selection was then calculated for each breeding trial, and was generally found to be low for the experiment-station sites. Further investigation showed that the non-station sites are suitable for the selection of genotypes intended for low-yielding environments, and the station sites are better suited for the selection of genotypes intended for high-yielding environments. The optimum selection scheme was found to consist of several unreplicated trials per year, and at least four trials per year are necessary to avoid the possibility of a negative heritability of the correlated response to selection.

Correlated response to selection of testosterone levels and immunocompetence in lines selected for avian personality

2011 ◽  
Vol 81 (5) ◽  
pp. 1055-1061 ◽  
Author(s):  
Kees van Oers ◽  
Katherine L. Buchanan ◽  
Tanja E. Thomas ◽  
Pieter J. Drent
Keyword(s):  
Correlated Response ◽  
Response To Selection ◽  
Testosterone Levels ◽  
Selection Of

scholarly journals The genetic analysis of the direct and correlated response to selection for chaetae in Drosophila melanogaster

1973 ◽  
Vol 22 (1) ◽  
pp. 1-7
Author(s):  
W. R. Scowcroft
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Analysis ◽  
Genetic Correlation ◽  
Statistical Approach ◽  
Correlated Response ◽  
Minor Importance ◽  
Response To Selection ◽  
Genetic Changes ◽  
Selection For ◽  
Selection Of

SUMMARYThe direct and correlated response to selection of scutellar microchaetae and scutellar bristles has been analysed by determining the contribution of the three major chromosomes, alone and in combination with each other, to the overall response. The results of the analysis confirm a previous finding, based on a formal statistical approach, that response to selection for microchaetae had highly pleiotropic effects on scutellar bristles. In lines selected, each for high and low microchaetae, genetic changes in the 2nd and 3rd chromosomes are pre-eminent and essentially equal. Inter-chromosomal interactions are of relatively minor importance in interpreting the response to selection for microchaetae but assume greater importance with respect to the correlated character. The results are discussed in terms of the genetic correlation between fitness and the character measured.

scholarly journals Marker-assisted selection using ridge regression

2000 ◽  
Vol 75 (2) ◽  
pp. 249-252 ◽  
Author(s):  
JOHN C. WHITTAKER ◽  
ROBIN THOMPSON ◽  
MIKE C. DENHAM
Keyword(s):  
Linear Regression ◽  
Ridge Regression ◽  
Marker Assisted Selection ◽  
Quantitative Traits ◽  
Selection Response ◽  
Inbred Lines ◽  
Response To Selection ◽  
Satisfactory Method ◽  
The Mean ◽  
Selection Of

In crosses between inbred lines, linear regression can be used to estimate the correlation of markers with a trait of interest; these marker effects then allow marker assisted selection (MAS) for quantitative traits. Usually a subset of markers to include in the model must be selected: no completely satisfactory method of doing this exists. We show that replacing this selection of markers by ridge regression can improve the mean response to selection and reduce the variability of selection response.

Estimation of Genetic Parameters and Selection Response for Reproductive and Growth Traits in Rideau-Arcott sheep

2020 ◽  
Author(s):  
Mohammed Naser Boareki ◽  
Luiz Brito ◽  
Angela Cánovas ◽  
V.R. Osborne ◽  
Flavio S Schenkel
Keyword(s):  
Litter Size ◽  
Genetic Parameters ◽  
Growth Traits ◽  
Reproductive Traits ◽  
Selection Response ◽  
Direct Selection ◽  
Correlated Response ◽  
Response To Selection ◽  
Weaning Weight ◽  
Selection For

The goal of this study was to estimate genetic parameters and predict direct and correlated response to selection for lamb growth traits and ewe reproductive traits, based on single trait selection or combining multiple traits in an optimum index that targets total litter post-weaning weight in the first lambing as the main selection goal. Heritability estimates ranged from 0.04 to 0.19. Genetic correlations between growth and reproductive traits ranged from -0.24 to 0.15. The indirect response to selection for reproductive traits in later lambings, by selecting on first lambing performance, was 11 to 25% greater than direct selection. The response to indirect selection for composite reproductive traits, i.e. total weaning weight or total post-weaning weight, by selecting on individual lamb weaning weight or post-weaning weight was 1 to 69% greater than direct selection, but it was accompanied by a negative response on litter size. However, combining alternate growth and reproductive traits in optimum selection index resulted in correlated response of up to 96% greater than direct selection response for reproductive traits without a negative response on litter size. Therefore, multiple trait selection using an index of component traits was more effective than direct selection for a composite trait.

scholarly journals Linear heritability estimates

1961 ◽  
Vol 2 (3) ◽  
pp. 439-448 ◽  
Author(s):  
Hans Abplanalp
Keyword(s):  
Genetic Correlation ◽  
The Other ◽  
Correlated Response ◽  
Response To Selection ◽  
Population Mean ◽  
Straight Line ◽  
The Mean ◽  
Heritability Estimates ◽  
Selection Of ◽  
Prospective Parents

A method for obtaining linear estimates of heritability and genetic correlation is given. It is based, essentially, on selecting, from a pedigreed population, prospective parents for which estimates of average genotype and phenotype values are obtained; a regression of genotype on phenotype value is then determined from a straight line fitted through points representing the population mean genotype and phenotype on one hand and the mean genotype and phenotype of selected parents on the other.The method permits an evaluation of asymmetry in response for a trait selected in both directions, as well as asymmetry in correlated response to selection of two different traits, with data from a single pedigreed population.

Efficiency of conversion of food to wool. I. Correlated response to selection for high and low clean wool weight

1960 ◽  
Vol 11 (5) ◽  
pp. 836 ◽  
Author(s):  
CHS Dolling ◽  
RW Moore
Keyword(s):  
The Other ◽  
Correlated Response ◽  
Response To Selection ◽  
Merino Sheep ◽  
Wool Production ◽  
The Family ◽  
Selection For ◽  
The Difference ◽  
Selection Of

The offspring of two families of medium Peppin Merino sheep, one family being selected for high and the other for low clean wool weight per head at 15-16 months of age under grazing conditions, have also been shown to differ significantly in the ratio of wool production to food eaten in pens, on a ration slightly above maintenance. These ratios were in the proportion 108 : 100, and the difference between the families can be taken as reflecting closely a difference in net efficiency of conversion of food to wool. It may be concluded that selection for high clean wool weight per head under grazing conditions had also resulted in the selection of more efficient animals. Clean wool production per head in the two families was in the ratio 110 : 100 in the pens, compared with 124 : 100 under grazing. The difference under grazing probably results from both the higher efficiency of the family selected for high clean wool weight and a higher grazing intake by this family.

ESTIMASI NILAI HERITABILITAS BOBOT IKAN MAS VARIETAS PUNTEN DALAM PROGRAM SELEKSI INDIVIDU

2016 ◽  
Vol 11 (3) ◽  
pp. 217
Author(s):  
Estu Nugroho ◽  
Budi Setyono ◽  
Mochammad Su’eb ◽  
Tri Heru Prihadi
Keyword(s):  
Body Weight ◽  
Selection Response ◽  
Base Population ◽  
Breeding Programs ◽  
Male And Female ◽  
Body Weight Trait ◽  
Population Selection ◽  
Selection For ◽  
Weight Trait ◽  
Selection Of

Program pemuliaan ikan mas varietas Punten dilakukan dengan seleksi individu terhadap karakter bobot ikan. Pembentukan populasi dasar untuk kegiatan seleksi dilakukan dengan memijahkan secara massal induk ikan mas yang terdiri atas 20 induk betina dan 21 induk jantan yang dikoleksi dari daerah Punten, Kepanjen (delapan betina dan enam jantan), Kediri (tujuh betina dan 12 jantan), Sragen (27 betina dan 10 jantan), dan Blitar (15 betina dan 11 jantan). Larva umur 10 hari dipelihara selama empat bulan. Selanjutnya dilakukan penjarangan sebesar 50% dan benih dipelihara selama 14 bulan untuk dilakukan seleksi dengan panduan hasil sampling 250 ekor individu setiap populasi. Seleksi terhadap calon induk dilakukan saat umur 18 bulan pada populasi jantan dan betina secara terpisah dengan memilih berdasarkan 10% bobot ikan yang terbaik. Calon induk yang terseleksi kemudian dipelihara hingga matang gonad, kemudian dipilih sebanyak 150 pasang dan dipijahkan secara massal. Didapatkan respons positif dari hasil seleksi berdasarkan bobot ikan, yaitu 49,89 g atau 3,66% (populasi ikan jantan) dan 168,47 g atau 11,43% (populasi ikan betina). Nilai heritabilitas untuk bobot ikan adalah 0,238 (jantan) dan 0,505 (betina).Punten carp breeding programs were carried out by individual selection for body weight trait. The base population for selection activities were conducted by mass breeding of parent consisted of 20 female and 21 male collected from area Punten, eight female and six male (Kepanjen), seven female and 12 male (Kediri), 27 female and 10 male (Sragen), 15 female and 11 male (Blitar). Larvae 10 days old reared for four moths. Then after spacing out 50% of total harvest, the offspring reared for 14 months for selection activity based on the sampling of 250 individual each population. Selection of broodstock candidates performed since 18 months age on male and female populations separately by selecting based on 10% of fish with best body weight. Candidates selected broodstocks were then maintained until mature. In oder to produce the next generation 150 pairs were sets and held for mass spawning. The results revealed that selection response were positive, 49.89 g (3.66%) for male and 168.47 (11.43%) for female. Heritability for body weight is 0.238 (male) and 0.505 (female).

Correlated response to selection for litter size in pigs: II. Carcass, meat, and fat quality traits

2002 ◽  
Vol 80 (10) ◽  
pp. 2566 ◽  
Author(s):  
J. Estany ◽  
D. Villalba ◽  
M. Tor ◽  
D. Cubiló ◽  
J. L. Noguera
Keyword(s):  
Litter Size ◽  
Correlated Response ◽  
Quality Traits ◽  
Response To Selection ◽  
Fat Quality ◽  
Selection For

scholarly journals Optimum Selection of Variable Pitch for Chatter Suppression in Face Milling Operations

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 112 ◽  
Author(s):  
Alex Iglesias ◽  
Zoltan Dombovari ◽  
German Gonzalez ◽  
Jokin Munoa ◽  
Gabor Stepan
Keyword(s):  
Removal Rate ◽  
Face Milling ◽  
Heavy Duty ◽  
Variable Pitch ◽  
Thin Walls ◽  
Chatter Suppression ◽  
Milling Operations ◽  
Optimum Selection ◽  
Cutting Capacity ◽  
Selection Of

Cutting capacity can be seriously limited in heavy duty face milling processes due to self-excited structural vibrations. Special geometry tools and, specifically, variable pitch milling tools have been extensively used in aeronautic applications with the purpose of removing these detrimental chatter vibrations, where high frequency chatter related to slender tools or thin walls limits productivity. However, the application of this technique in heavy duty face milling operations has not been thoroughly explored. In this paper, a method for the definition of the optimum angles between inserts is presented, based on the optimum pitch angle and the stabilizability diagrams. These diagrams are obtained through the brute force (BF) iterative method, which basically consists of an iterative maximization of the stability by using the semidiscretization method. From the observed results, hints for the selection of the optimum pitch pattern and the optimum values of the angles between inserts are presented. A practical application is implemented and the cutting performance when using an optimized variable pitch tool is assessed. It is concluded that with an optimum selection of the pitch, the material removal rate can be improved up to three times. Finally, the existence of two more different stability lobe families related to the saddle-node and flip type stability losses is demonstrated.

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