scholarly journals A method for partitioning trends in genetic mean and variance to understand breeding practices

2022 ◽  
Author(s):  
Thiago de Paula Oliveira ◽  
Jana Obsteter ◽  
Ivan Pocrnic ◽  
Gregor Gorjanc
Keyword(s):  
Genetic Variance ◽  
Genetic Change ◽  
Breeding Programmes ◽  
Mean And Variance ◽  
Breeding Practices ◽  
Breeding Groups

Quantifying the sources of genetic change is essential for optimising breeding programmes. However, breeding programmes are often complex because many breeding groups are subject to different breeding actions. Understanding the contribution of these groups to changes in genetic mean and variance is essential to understanding genetic change in breeding programmes. Here we extend the previously developed method for analysing the contribution of groups to changes in genetic mean to analysing changes in genetic variance. We, expectedly, show that the contribution of females and males to change in genetic variance can differ and are not independent, indicating we should not look at the contributions in isolation.

scholarly journals Genetic worth of multiple sets of cowpea breeding lines destined for advanced yield testing

Euphytica ◽  
2021 ◽  
Vol 217 (2) ◽  
Author(s):  
Patrick Obia Ongom ◽  
Christian Fatokun ◽  
Abou Togola ◽  
Oluwaseye Gideon Oyebode ◽  
Mansur Sani Ahmad ◽  
...  
Keyword(s):  
Seed Weight ◽  
Genetic Variance ◽  
Principal Component ◽  
Performance Tests ◽  
Genetic Advance ◽  
Breeding Lines ◽  
Lattice Design ◽  
Mean And Variance ◽  
Genotypic Coefficient Of Variation ◽  
Location Interaction

AbstractThe objective of this study was to determine genetic potentials in eight sets of cowpea lines for grain yield (GY), hundred seed weight (HSDWT) and days to 50% flowering (DT50FL). A total of 614 F6 genotypes constituting the sets, grouped by maturity, were evaluated across two locations in Northern Nigeria, in an alpha lattice design, two replications each. Data were recorded on GY, HSDWT and DT50FL.Variance components, genotypic coefficient of variation (GCV), and genetic advance (GA) were used to decode the magnitude of genetic variance within and among sets. Genetic usefulness (Up) which depends on mean and variance to score the genetic merits in historically bi-parental populations was applied to groups of breeding lines with mixed parentage. Principal component analysis (PCA) was used to depict contribution of traits to observed variations. GY and DT50FL explained the variance within and between sets respectively. Genotypes were significantly different, although genotype-by-location and set-by-location interaction effects were also prominent. Genetic variance (δ2G) and GCV were high for GY in Prelim2 (δ2G = 45,897; GCV = 19.58%), HSDWT in Prelim11 (δ2G = 7.137; GCV = 17.07%) and DT50F in Prelim5 (δ2G = 4.54; GCV = 4.4%). Heritability varied among sets for GY (H = 0.21 to 0.57), HSDWT (H = 0.76 to 0.93) and DT50FL (H = 0.20 to 0.81). GA and percentage GA (GAPM) were high for GY in Prelim2 (GAPM = 24.59%; GA = 269.05Kg/ha), HSDWT in Prelim11 (GAPM = 28.54%; GA = 4.47 g), and DT50F in Prelim10 (GAPM = 6.49%; GA = 3.01 days). These sets also registered high values of genetic usefulness, suggesting potential application in non-full sib populations. These approaches can be used during preliminary performance tests to reinforce decisions in extracting promising lines and choose among defined groups of lines.

Policy of selecting bulls to breed bulls

1987 ◽  
Vol 44 (1) ◽  
pp. 29-38 ◽  
Author(s):  
M. E. Goddard
Keyword(s):  
Dairy Cattle ◽  
Genetic Variance ◽  
Selection Response ◽  
Progeny Testing ◽  
Cattle Breeding ◽  
Sire Evaluation ◽  
Dairy Cattle Breeding ◽  
Breeding Programmes ◽  
Computer Simulation Program ◽  
Selection Of

ABSTRACTIn the breeding of dairy cattle the selection of bulls to breed young bulls for progeny testing is a crucial process. This paper compares several policies for making this selection based on the criteria-selection response, inbreeding depression, loss of genetic variance and variability of response. A number called the ‘effective number of new bulls to breed bulls selected each year’ (NBBe) is defined which is closely related to the last three of these criteria. Past studies of the design of dairy cattle breeding programmes have assumed that selection is within a group of bulls progeny tested in the same year (policy I). However, modern sire evaluation methods allow comparison of sires tested in different years. To evaluate the effect of selecting bulls to breed bulls from all available bulls (policy II) a computer simulation program was used. Policy II results in an increase in the response to selection but a substantial decrease in NBBe. When compared at the same NBBe, policy II results in a smaller selection response than policy I. A policy which allows the best bulls to be used for more than 1 year but which limits the maximum number of years for which they can be used, results in the best compromise. If bulls are to be used for several years there is little advantage to be gained from making more matings within each year to more high-rated bulls or to older, more reliably evaluated bulls.

scholarly journals Effects on phenotypic variability of directional selection arising through genetic differences in residual variability

2004 ◽  
Vol 83 (2) ◽  
pp. 121-132 ◽  
Author(s):  
WILLIAM G. HILL ◽  
XU-SHENG ZHANG
Keyword(s):  
Genetic Variance ◽  
Environmental Variability ◽  
Phenotypic Variability ◽  
Additive Genetic Variance ◽  
Directional Selection ◽  
Frequency Change ◽  
Phenotypic Variance ◽  
Additive Effects ◽  
Genetic Covariance ◽  
Mean And Variance

In standard models of quantitative traits, genotypes are assumed to differ in mean but not variance of the trait. Here we consider directional selection for a quantitative trait for which genotypes also confer differences in variability, viewed either as differences in residual phenotypic variance when individual loci are concerned or as differences in environmental variability when the whole genome is considered. At an individual locus with additive effects, the selective value of the increasing allele is given by ia/σ+½ixb/σ2, where i is the selection intensity, x is the standardized truncation point, σ2 is the phenotypic variance, and a/σ and b/σ2 are the standardized differences in mean and variance respectively between genotypes at the locus. Assuming additive effects on mean and variance across loci, the response to selection on phenotype in mean is iσAm2/σ+½ixcovAmv/σ2 and in variance is icovAmv/σ+½ixσ2Av/σ2, where σAm2 is the (usual) additive genetic variance of effects of genes on the mean, σ2Av is the corresponding additive genetic variance of their effects on the variance, and covAmv is the additive genetic covariance of their effects. Changes in variance also have to be corrected for any changes due to gene frequency change and for the Bulmer effect, and relevant formulae are given. It is shown that effects on variance are likely to be greatest when selection is intense and when selection is on individual phenotype or within family deviation rather than on family mean performance. The evidence for and implications of such variability in variance are discussed.

Production, fertility and hatchability of ostrich (Struthio camelus) eggs on a farm in the United Kingdom

1996 ◽  
Vol 63 (2) ◽  
pp. 329-336 ◽  
Author(s):  
D. C. Deeming
Keyword(s):  
South Africa ◽  
United Kingdom ◽  
Egg Production ◽  
Microbial Contamination ◽  
Scientific Data ◽  
Factors Affecting ◽  
The United Kingdom ◽  
Breeding Programmes ◽  
Cause Of Failure ◽  
Breeding Groups

AbstractThe farming of ostriches is well established in South Africa and is gaining in popularity in agriculture around the world but few scientific data are available for rates of egg production and the factors affecting incubation and hatching. Production and hatchability of over 1200 ostrich eggs on a farm in the United Kingdom were recorded during the 1995 season. Females of breeding ages (no. = 43) were kept in 13 enclosures in sex ratios of 1: 1 or 1: 2 (M: F). Productivity of all ostriches over the laying season was 25·2% although when results from individual enclosures, and from individual birds, were examined higher rates of production were achieved although only one bird achieved her full laying potential. As group size increased productivity decreased. Overall fertility was 78·7% although fertility greater than 90% was achieved by females kept in pairs or trios. Larger group sizes had lower fertility. Mean weekly hatchability was only 24·1% with hatch of fertile eggs being 31·9%. Maximum hatchability of eggs produced from an individual female was 73% of fertile eggs. Microbial contamination of eggs was 32·6% and this was the biggest cause of failure to hatch, although rates of contamination varied between females. These results for productivity are similar to those published for ostriches in Israel and South Africa. Hatchability is lower, and microbial contamination is higher than published information although this is the most comprehensive study of ostrich production yet published. Future development of ostrich breeding programmes needs to concentrate on small breeding groups, preferably pairs, and on improvements in nest site hygiene and post-laying egg management.

Association of Twin Zygosity With the Mean and Variance of Tooth Size

1979 ◽  
Vol 28 (3) ◽  
pp. 211-223 ◽  
Author(s):  
Rosario H. Yap Potter ◽  
Pao-lo Yu ◽  
Joe C. Christian
Keyword(s):  
Genetic Variance ◽  
T Test ◽  
Tooth Size ◽  
F Test ◽  
Sex Influence ◽  
Mean And Variance ◽  
The Mean ◽  
Variance Estimates

To search for an association of twin zygosity with tooth size, 56 dental variables measured from 65 pairs of twins (43 MZ, 22 DZ) were studied. Results of the t′ test for equality of the means showed no association of zygosity with any of the variables in males or in females. Results of the F′ test for homogeneity of total variances between zygosities showed evidence for unequal total variances in 15 variables in males and 13 in females. Sex influence was further noted on the association of zygosity with the variance of tooth size. Where total variances were unequal, genetic variance estimates differed when only the within-pair mean squares were used and when combined estimates designed to be unbiased by differences in environmental variances were used.

scholarly journals Genomic mating in outbred species: predicting cross usefulness with additive and total genetic covariance matrices

Genetics ◽  
2021 ◽  
Author(s):  
Marnin D Wolfe ◽  
Ariel W Chan ◽  
Peter Kulakow ◽  
Ismail Rabbi ◽  
Jean-Luc Jannink
Keyword(s):  
Mate Selection ◽  
Selection Criteria ◽  
Genetic Variance ◽  
Selection Index ◽  
Dominance Model ◽  
Genetic Covariance ◽  
Good Correspondence ◽  
Mean And Variance ◽  
Genetic Distribution ◽  
Selection Of

Abstract Diverse crops are both outbred and clonally propagated. Breeders typically use truncation selection of parents and invest significant time, land and money evaluating the progeny of crosses to find exceptional genotypes. We developed and tested genomic mate selection criteria suitable for organisms of arbitrary homozygosity level where the full-sibling progeny are of direct interest as future parents and/or cultivars. We extended cross variance and covariance variance prediction to include dominance effects and predicted the multivariate selection index genetic variance of crosses based on haplotypes of proposed parents, marker effects and recombination frequencies. We combined the predicted mean and variance into usefulness criteria for parent and variety development. We present an empirical study of cassava (Manihot esculenta), a staple tropical root crop. We assessed the potential to predict the multivariate genetic distribution (means, variances and trait covariances) of 462 cassava families in terms of additive and total value using cross-validation. Most variance (89%) and covariance (70%) prediction accuracy estimates were greater than zero. The usefulness of crosses were accurately predicted with good correspondence between the predicted and the actual mean performance of family members breeders selected for advancement as new parents and candidate varieties. We also used a directional dominance model to quantify significant inbreeding depression for most traits. We predicted 47,083 possible crosses of 306 parents and contrasted them to those previously tested to show how mate selection can reveal new potential within the germplasm. We enable breeders to consider the potential of crosses to produce future parents (progeny with top breeding values) and varieties (progeny with top own performance).

scholarly journals KARAKTER GENOTIPE TIGA POPULASI IKAN RAINBOW AJAMARU (Melanotaenia ajamaruensis) DARI ALAM DAN BUDIDAYA MENGGUNAKAN RAPD

2018 ◽  
Vol 13 (2) ◽  
pp. 105
Author(s):  
Erma Primanita Hayuningtyas ◽  
Shofihar Sinansari ◽  
Melta Rini Fahmi ◽  
Eni Kusrini ◽  
Bastiar Nur
Keyword(s):  
Dna Polymorphism ◽  
Genetic Variance ◽  
Genetic Change ◽  
Wild Fish ◽  
Fish Culture ◽  
Ex Situ ◽  
Randomly Amplified Polymorphic Dna ◽  
Cultured Fish ◽  
In The Wild ◽  
High Genetic Distance

Ikan rainbow Ajamaru (Melanotaenia ajamarunensis) yang dinyatakan punah pada tahun 1996 merupakan ikan endemik dari Danau Ajamaru, Papua. Namun ikan ini berhasil ditemukan kembali pada tahun 2007 di Sungai Kaliwensi, Sorong, Papua. Domestikasi ex-situ ikan rainbow Ajamaru sedang dilakukan di Balai Riset Budidaya ikan Hias, Depok-Jawa Barat. Penelitian ini bertujuan mengevaluasi perbedaan genotipe ikan rainbow Ajamaru di alam dan budidaya melalui analisis keragaman genetik untuk melihat adanya perubahan genetik, migrasi maupun mutasi gen. Metode yang digunakan adalah Randomly Amplified Polymorphic DNA (RAPD) dengan 3 jenis primer (OPA 03, OPB 6, dan OPZ 5). Setiap populasi baik, dari alam (Papua) maupun budidaya (Depok dan Papua) masing-masing diambil secara acak sebanyak 10 sampel ikan uji. Hasil penelitian menunjukkan nilai keragaman genetik pada ikan di alam lebih rendah (62,5%) dibanding ikan budidaya di Papua (70,31%) dan tertinggi pada ikan budidaya di Depok (73,43%). Heterozigositas pada ikan di alam lebih rendah (0,172) dibanding ikan budidaya di Papua (0,241) dan di Depok (0,270). Jarak genetik terjauh ditunjukkan antara populasi ikan alam dan populasi ikan budidaya Papua, sedangkan jarak genetik terdekat antara populasi ikan budidaya di Papua dengan di Depok. Karakter genotipe yang dihasilkan pada tiga populasi ikan rainbow Ajamaru adalah memiliki corak DNA yang berbeda nyata (P<0,05). Perbedaan yang dihasilkan dari karakter genotipe karena respon genotip dari tiap individu dan daya adaptasi ikan berbeda-beda pada habitat yang berbeda.Ajamaru rainbow, an endemic fish from Lake Ajamaru, Papua, once declared extinct in 1996. However, it was rediscovered in 2007, in Kaliwensi River, Sorong, Papua. Currently, the Ajamaru rainbow fish is being domesticated ex-situ at the Research Center for Ornamental Fish Culture, Depok, West Java. The aim of the research was to determine the genotype characteristics of wild and cultured Ajamaru rainbow including genetic change, drift, migration, and mutation using genetic variance analysis. The genetic analysis applied was Randomly Amplified Polymorphic DNA (RAPD) using OPA-03, OPB-6, and OPZ-5 primers. Ten samples were used for each population. The results showed that the three populations of Ajamaru rainbow fish have significantly different (P<0.05) of DNA polymorphism. The lowest value of genetic variance was found in the wild fish (62.5%) followed by the cultured fish located in Papua (70.31%), and the highest was observed in the cultured fish located in Depok (73.43%). Heterozygosity of the wild fish was lower (0.172) than that of the cultured fish in Papua (0.241) and in Depok (0.270). The high genetic distance was found between the wild and cultured fish from Papua. The closest relationship was between the fish culture in Papua and Depok. The genotype character produced in the three Ajamaru rainbow fish populations was have significantly different (P<0.05) of DNA polymorphism. The differences that result form genotype characters because of the genotypic response of each individual and the adaptability of fish vary in different habitats. 

scholarly journals The inheritance of metabolic flux: expressions for the within-sibship mean and variance given the parental genotypes.

Genetics ◽  
1990 ◽  
Vol 125 (3) ◽  
pp. 655-667
Author(s):  
P J Ward
Keyword(s):  
Statistical Power ◽  
Metabolic Flux ◽  
Genetic Variance ◽  
Small Sample ◽  
Polygenic Inheritance ◽  
Allozymic Variation ◽  
Recent Developments ◽  
Mean And Variance ◽  
Small Sample Sizes ◽  
Adequate Power

Abstract Recent developments have related quantitative trait expression to metabolic flux. The present paper investigates some implications of this for statistical aspects of polygenic inheritance. Expressions are derived for the within-sibship genetic mean and genetic variance of metabolic flux given a pair of parental, diploid, n-locus genotypes. These are exact and hold for arbitrary numbers of gene loci, arbitrary allelic values at each locus, and for arbitrary recombination fractions between adjacent gene loci. The within-sibship, genetic variance is seen to be simply a measure of parental heterozygosity plus a measure of the degree of linkage coupling within the parental genotypes. Approximations are given for the within-sibship phenotypic mean and variance of metabolic flux. These results are applied to the problem of attaining adequate statistical power in a test of association between allozymic variation and inter-individual variation in metabolic flux. Simulations indicate that statistical power can be greatly increased by augmenting the data with predictions and observations on progeny statistics in relation to parental allozyme genotypes. Adequate power may thus be attainable at small sample sizes, and when allozymic variation is scored at a only small fraction of the total set of loci whose catalytic products determine the flux.

scholarly journals On the distribution of the mean and variance of a quantitative trait under mutation-selection-drift balance.

Genetics ◽  
1994 ◽  
Vol 138 (3) ◽  
pp. 901-912 ◽  
Author(s):  
R Bürger ◽  
R Lande
Keyword(s):  
Genetic Drift ◽  
Quantitative Trait ◽  
Quantitative Traits ◽  
Genetic Variance ◽  
Stochastic Simulations ◽  
Stabilizing Selection ◽  
Phenotypic Evolution ◽  
Theoretical Predictions ◽  
Mean And Variance ◽  
The Mean

Abstract The distributions of the mean phenotype and of the genetic variance of a polygenic trait under a balance between mutation, stabilizing selection and genetic drift are investigated. This is done by stochastic simulations in which each individual and each gene are represented. The results are compared with theoretical predictions. Some aspects of the existing theories for the evolution of quantitative traits are discussed. The maintenance of genetic variance and the average dynamics of phenotypic evolution in finite populations (with Ne &lt; 1000) are generally simpler than those suggested by some recent deterministic theories for infinite populations.

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