scholarly journals Early Selection of Radiata Pine

2006 ◽  
Vol 55 (1-6) ◽  
pp. 182-191 ◽  
Author(s):  
C. A. Dean ◽  
P. P. Cotterill ◽  
R. D. Burdon
Keyword(s):  
Genetic Control ◽  
Genetic Variance ◽  
Genetic Correlations ◽  
Radiata Pine ◽  
Phenotypic Variance ◽  
Sectional Area ◽  
Growth Data ◽  
Additive Variance ◽  
Half Diallel ◽  
Selection Of

Abstract Additive genetic, dominance genetic and phenotypic variances and corresponding correlations were estimated for growth data collected from disconnected half-diallel progeny trials involving 25 Pinus radiata D. DON parents and replicated across two sites in central North Island, New Zealand. Sectional area of stem was measured at three, seven, 10 and 13 years after planting at both sites, and height at three and 10 years at one site. Sectional area at three years exhibited similar levels of estimated additive (σA2) and dominance (σD2) genetic variance. However, levels of σD2 remained approximately constant between three and 13 years while σA2 increased substantially. Thus, sectional-area growth changed from being under equal additive and dominance genetic control at three years to almost complete additive genetic control from seven to 13 years. The greater increase in additive variance relative to phenotypic variance led to increases in individual heritability from 0.16 to 0.28 to 0.35 for sectional-area increments between 3-7, 7-10 and 10-13 years, respectively. Height growth exhibited negligible levels of σD2 for the three- and 10-year measurements. The early sectional-area increment between 3-7 years showed an estimated additive genetic correlation of 0.87 with “mature” sectional area at 13 years. Subsequent sectional-area increments between 7-10 and 10-13 years showed estimates of additive genetic correlations of 0.99 with sectional area at 13 years. Dominance genetic correlations were much lower in magnitude, reflecting inconsistent dominance effects over time.

The incorporation of fertility indices in genetic improvement programmes

2001 ◽  
Vol 26 (1) ◽  
pp. 237-249 ◽  
Author(s):  
J.E. Pryce ◽  
R.F. Veerkamp
Keyword(s):  
Genetic Variance ◽  
Selection Index ◽  
Genetic Correlations ◽  
Live Weight ◽  
Parameter Estimates ◽  
Phenotypic Variance ◽  
Production Traits ◽  
Genetic Progress ◽  
Detection Rates ◽  
Days Open

AbstractIn recent years there has been considerable genetic progress in milk production. Yet, increases in yield have been accompanied by an apparent lengthening of calving intervals, days open, days to first heat and a decline in conception rates, which appears to be both at the genetic and phenotypic level. Fertility has a high relative economic value compared to production traits such as protein, making it attractive to include in a breeding programme. To do this there needs to be genetic variance in fertility. Measures of fertility calculated from service dates have a small genetic compared to phenotypic variance, hence heritability estimates are small, typically less than 5%, although coefficients of genetic variance are comparable to those of production traits. Heritabilities of commencement of luteal activity determined using progesterone profiles are generally higher, and have been reported as being from 0.16 to 0.28, which could be because of a more precise quantification of genetic variance, as management influences such as delaying insemination and heat detection rates are excluded. However, it might not be the use of progesterone profiles alone, as days to first heat observed by farm staff has a heritability of 0.15. The most efficient way to breed for improved fertility is to construct a selection index using the genetic and phenotypic parameter estimates of all traits of interest in addition to their respective economic values. Index traits for fertility could include measures such as calving interval, days open, days to first service, or days to first heat but there may also be alternative measures. Examples include traits related to energy balance, such as live weight and condition score (change), both of which have higher heritabilities than fertility measures and have genetic correlations of sufficient magnitude to make genetic progress by using them feasible. To redress the balance between fertility and production, some countries already publish genetic evaluations of fertility including: Denmark, Finland, France, Germany, Israel, The Netherlands, Norway and Sweden.

scholarly journals Polygenic Architecture of Human Neuroanatomical Diversity

2020 ◽  
Vol 30 (4) ◽  
pp. 2307-2320
Author(s):  
Anne Biton ◽  
Nicolas Traut ◽  
Jean-Baptiste Poline ◽  
Benjamin S Aribisala ◽  
Mark E Bastin ◽  
...  
Keyword(s):  
Genetic Variance ◽  
Meta Analysis ◽  
Genetic Correlations ◽  
Global Scale ◽  
Phenotypic Variance ◽  
Environmental Correlations ◽  
Genomic Architecture ◽  
Snp Data ◽  
Environmental Causes ◽  
The Uk

Abstract We analyzed the genomic architecture of neuroanatomical diversity using magnetic resonance imaging and single nucleotide polymorphism (SNP) data from >26 000 individuals from the UK Biobank project and 5 other projects that had previously participated in the ENIGMA (Enhancing NeuroImaging Genetics through Meta-Analysis) consortium. Our results confirm the polygenic architecture of neuroanatomical diversity, with SNPs capturing from 40% to 54% of regional brain volume variance. Chromosomal length correlated with the amount of phenotypic variance captured, r ~ 0.64 on average, suggesting that at a global scale causal variants are homogeneously distributed across the genome. At a local scale, SNPs within genes (~51%) captured ~1.5 times more genetic variance than the rest, and SNPs with low minor allele frequency (MAF) captured less variance than the rest: the 40% of SNPs with MAF <5% captured <one fourth of the genetic variance. We also observed extensive pleiotropy across regions, with an average genetic correlation of rG ~ 0.45. Genetic correlations were similar to phenotypic and environmental correlations; however, genetic correlations were often larger than phenotypic correlations for the left/right volumes of the same region. The heritability of differences in left/right volumes was generally not statistically significant, suggesting an important influence of environmental causes in the variability of brain asymmetry. Our code is available athttps://github.com/neuroanatomy/genomic-architecture.

Genetic control of quality traits of lucerne (Medicago sativa L.)

2002 ◽  
Vol 53 (4) ◽  
pp. 401 ◽  
Author(s):  
F. Guines ◽  
B. Julier ◽  
C. Ecalle ◽  
C. Huyghe
Keyword(s):  
Protein Content ◽  
Genetic Control ◽  
Plant Height ◽  
Combining Ability ◽  
Genetic Correlations ◽  
Additive Variance ◽  
Dry Matter Digestibility ◽  
Acid Detergent Fibre ◽  
Feeding Value ◽  
Female Effect

An important objective in lucerne breeding is the improvement of feeding value. An understanding of the inheritance of digestibility and cell wall related traits would facilitate the breeding of varieties with higher feeding value. The aim of this experiment was first to determine the genetic control of dry matter digestibility and related biochemical and morphological traits, and to assess phenotypic and genetic correlations between these traits. Quantitative genetic parameters were estimated for enzymatic solubility, neutral detergent fibre (NDF), acid detergent fibre (ADF), acid detergent lignin (ADL), protein content, plant height, and leaf-to-stem ratio. A 7 × 7 diallel design with reciprocals and without selfing among parents from different populations and a 7 × 7 factorial design within the ‘Flamande’ population were studied. In the diallel study, effects due to general combining ability (GCA) were higher than those due to specific combining ability (SCA) for all characters tested. In the factorial study, the F1 progeny effect was significant for all characters. The male effect was highly significant for all traits and higher than the female effect except for plant height. The additive variance was higher than the dominance variance for all characters except for plant height. The inheritance was predominantly additive. The highest narrowsense heritabilities were found for NDF and ADF and leaf-to-stem ratio. As a consequence, NDF or ADF would be more efficient selection criteria than enzymatic solubility in a breeding program for improved feeding value. In both mating designs, NDF, ADF, and ADL were positively correlated with one another and negatively with enzymatic solubility and protein content.

scholarly journals Genetic Control of O3 Sensitivity in a Cross Between Two Cultivars of Snap Bean

2000 ◽  
Vol 125 (2) ◽  
pp. 222-227 ◽  
Author(s):  
Richard A. Reinert ◽  
Gwen Eason
Keyword(s):  
Genetic Control ◽  
Genetic Variance ◽  
Additive Genetic Variance ◽  
Phenotypic Variance ◽  
Narrow Sense Heritability ◽  
Snap Bean ◽  
Reciprocal Crosses ◽  
Blue Lake ◽  
Environmental Component ◽  
Variance Estimates

Identification of genetic control of ozone (O3) sensitivity is desirable for selection of plant cultivars which are indicators of O3 stress. A cross was made between two cultivars of snap bean (Phaseolus vulgaris L.), `Oregon 91' (P1) and `Wade Bush' (P2), an O3-sensitive and O3-insensitive cultivar, respectively. Ten genetic populations (generations), `Oregon 91' (P1), `Wade Bush' (P2), F1, F2, backcrosses to both parents, and all reciprocal crosses, were field planted in each of two summers and evaluated for injury to O3. Ozone responses for the reciprocal crosses were not significantly different for any generation, so injury ratings from the reciprocal crosses were combined for each generation to provide six populations (P1, P2, F1, F2, BC1, and BC2) for analysis. When components of genetic variation were estimated from the six generations, additive genetic variance was the most important component in the total genetic variance available, although dominance variance was also a significant component. There was an inconsistency in the magnitude and the direction of the factors contributing to the dominance effects and also a large environmental component making up the phenotypic variance. Estimates of broad-sense heritability and narrow-sense heritability were 60% and 44%, respectively. Results suggest that O3-sensitive and O3-insensitive selections could be screened and evaluated in an ambient O3 environment. Several generations will be necessary, however, to develop `Bush Blue Lake' type selections that vary only in sensitivity to O3.

scholarly journals Polygenic architecture of human neuroanatomical diversity

2019 ◽  
Author(s):  
Anne Biton ◽  
Nicolas Traut ◽  
Jean-Baptiste Poline ◽  
Benjamin S. Aribisala ◽  
Mark E. Bastin ◽  
...  
Keyword(s):  
Genetic Variance ◽  
Genetic Correlations ◽  
Global Scale ◽  
Phenotypic Variance ◽  
Environmental Correlations ◽  
Genomic Architecture ◽  
Snp Data ◽  
Causal Variants ◽  
Environmental Causes ◽  
The Uk

AbstractWe analysed the genomic architecture of neuroanatomical diversity using magnetic resonance imaging and single nucleotide polymorphism (SNP) data from >26,000 individuals from the UK Biobank project and 5 other projects that had previously participated in the ENIGMA consortium. Our results confirm the polygenic architecture of neuroanatomical diversity, with SNPs capturing from 40% to 54% of regional brain volume variance. Chromosomal length correlated with the amount of phenotypic variance captured, r∼0.64 on average, suggesting that at a global scale causal variants are homogeneously distributed across the genome. At a local scale, SNPs within genes (∼51%) captured ∼1.5 times more genetic variance than the rest; and SNPs with low minor allele frequency (MAF) captured less variance than the rest: the 40% of SNPs with MAF<5% captured <1/4th of the genetic variance. We also observed extensive pleiotropy across regions, with an average genetic correlation of rG∼0.45. Genetic correlations were similar to phenotypic and environmental correlations, however, genetic correlations were often larger than phenotypic correlations for the left/right volumes of the same region. The heritability of differences in left/right volumes was generally not statistically significant, suggesting an important influence of environmental causes in the variability of brain asymmetry. Our code is available at https://github.com/neuroanatomy/genomic-architecture.

Marker-assisted selection in an outbred poultry breeding nucleus

1996 ◽  
Vol 62 (1) ◽  
pp. 171-180 ◽  
Author(s):  
S. van der Beck ◽  
J. A. M. van Arendonk
Keyword(s):  
Genetic Variance ◽  
Genetic Model ◽  
Phenotypic Variance ◽  
Family Selection ◽  
Poultry Breeding ◽  
Cumulative Response ◽  
Trait Locus ◽  
Final Selection ◽  
Selection Of ◽  
Variance Explained

AbstractThe value of using a marker for a quantitative trait locus (QTL) affecting a sex-limited trait in an outbred poultry breeding nucleus was studied. Marker and QTL were in linkage equilibrium in the base population. The recombination rate between marker and QTL was 0-05. A closed nucleus with 9000 chickens per generation was deterministically simulated. The genetic model contained polygenes and a QTL linked to a marker. Genetic effects explained proportionately 0·3 of the phenotypic variance before selection. Under selection, polygenic variance reached an equilibrium and QTL variance decreased continuously over time. Cocks were selected in two steps. First the best cocks of each full-sib family were selected (within-family selection) while final selection took place after information on fiill-sibs was available. Hens were selected after they had completed production. The effect of using marker information in estimating breeding values was studied in an ongoing breeding programme. Transmission of marker alleles was always traceable. Cumulative response over five generations increased proportionately by 0·06 to 0·13 if a marker linked to a QTL that explained 0·2 of the genetic variance was used. Cumulative response increased up to 0·28 if the QTL explained 0-8 of the genetic variance. Additional response due to the use of a marker increased with increasing intensity of within-family selection of cocks, increased with increasing variance explained by the QTL and was higher if within-family selection of cocks was carried out after rather than before their sibs had complete records.

scholarly journals Additive and Dominance Genomic Analysis for Litter Size in Purebred and Crossbred Iberian Pigs

Genes ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 12
Author(s):  
Houssemeddine Srihi ◽  
José Luis Noguera ◽  
Victoria Topayan ◽  
Melani Martín de Hijas ◽  
Noelia Ibañez-Escriche ◽  
...  
Keyword(s):  
Litter Size ◽  
Genetic Variance ◽  
Mixed Model ◽  
Additive Genetic Variance ◽  
Genetic Correlations ◽  
Genomic Analysis ◽  
Gxe Interaction ◽  
Genomic Regions ◽  
Additive Genetic Effects ◽  
Selection Of

INGA FOOD S. A., as a Spanish company that produces and commercializes fattened pigs, has produced a hybrid Iberian sow called CASTÚA by crossing the Retinto and Entrepelado varieties. The selection of the parental populations is based on selection criteria calculated from purebred information, under the assumption that the genetic correlation between purebred and crossbred performance is high; however, these correlations can be less than one because of a GxE interaction or the presence of non-additive genetic effects. This study estimated the additive and dominance variances of the purebred and crossbred populations for litter size, and calculated the additive genetic correlations between the purebred and crossbred performances. The dataset consisted of 2030 litters from the Entrepelado population, 1977 litters from the Retinto population, and 1958 litters from the crossbred population. The individuals were genotyped with a GeneSeek® GGP Porcine70K HDchip. The model of analysis was a ‘biological’ multivariate mixed model that included additive and dominance SNP effects. The estimates of the additive genotypic variance for the total number born (TNB) were 0.248, 0.282 and 0.546 for the Entrepelado, Retinto and Crossbred populations, respectively. The estimates of the dominance genotypic variances were 0.177, 0.172 and 0.262 for the Entrepelado, Retinto and Crossbred populations. The results for the number born alive (NBA) were similar. The genetic correlations between the purebred and crossbred performance for TNB and NBA—between the brackets—were 0.663 in the Entrepelado and 0.881 in Retinto poplulations. After backsolving to obtain estimates of the SNP effects, the additive genetic variance associated with genomic regions containing 30 SNPs was estimated, and we identified four genomic regions that each explained > 2% of the additive genetic variance in chromosomes (SSC) 6, 8 and 12: one region in SSC6, two regions in SSC8, and one region in SSC12.

scholarly journals Genetic variance for body size in a natural population of Drosophila buzzatii.

Genetics ◽  
1991 ◽  
Vol 128 (4) ◽  
pp. 739-750
Author(s):  
A Ruiz ◽  
M Santos ◽  
A Barbadilla ◽  
J E Quezada-Díaz ◽  
E Hasson ◽  
...  
Keyword(s):  
Genetic Variance ◽  
Genetic Model ◽  
Phenotypic Variance ◽  
Total Phenotypic Variance ◽  
Fourth Chromosome ◽  
Narrow Sense Heritability ◽  
Additive Variance ◽  
Thorax Length ◽  
Drosophila Buzzatii ◽  
F2 Generation

Abstract Previous work has shown thorax length to be under directional selection in the Drosophila buzzatii population of Carboneras. In order to predict the genetic consequences of natural selection, genetic variation for this trait was investigated in two ways. First, narrow sense heritability was estimated in the laboratory F2 generation of a sample of wild flies by means of the offspring-parent regression. A relatively high value, 0.59, was obtained. Because the phenotypic variance of wild flies was 7-9 times that of the flies raised in the laboratory, "natural" heritability may be estimated as one-seventh to one-ninth that value. Second, the contribution of the second and fourth chromosomes, which are polymorphic for paracentric inversions, to the genetic variance of thorax length was estimated in the field and in the laboratory. This was done with the assistance of a simple genetic model which shows that the variance among chromosome arrangements and the variance among karyotypes provide minimum estimates of the chromosome's contribution to the additive and genetic variances of the trait, respectively. In males raised under optimal conditions in the laboratory, the variance among second-chromosome karyotypes accounted for 11.43% of the total phenotypic variance and most of this variance was additive; by contrast, the contribution of the fourth chromosome was nonsignificant. The variance among second-chromosome karyotypes accounted for 1.56-1.78% of the total phenotypic variance in wild males and was nonsignificant in wild females. The variance among fourth chromosome karyotypes accounted for 0.14-3.48% of the total phenotypic variance in wild flies. At both chromosomes, the proportion of additive variance was higher in mating flies than in nonmating flies.

ESTIMATING HERITABILITY OF FAMILIES DERIVED FROM SINGLE PLANTS AT AN ADVANCED GENERATION OF SELF-FERTILIZING SPECIES: DEVELOPING GENERAL FORMULAS AND ESTIMATING SPRING WHEAT TRAITS

1998 ◽  
Vol 46 (3) ◽  
pp. 209-212
Author(s):  
Alex Beharav ◽  
Moshe Pinthus J. ◽  
Avigdor Cahaner
Keyword(s):  
Spring Wheat ◽  
Variance Components ◽  
Genetic Variance ◽  
Heading Date ◽  
Phenotypic Variance ◽  
Additive Variance ◽  
Dominance Variance ◽  
Total Genetic Variance ◽  
Two Populations ◽  
Advanced Generation

Genetic expectations of total genetic variance, and between-family and within-family variance components were developed for any given generation (Fn) derived from single selfed plants of an earlier generation (Fk). A formula to estimate the heritability (h2) in any desired generation (Fn) was developed on the basis of these expectations. This formula estimates the value of the genetic variance from the phenotypic variance adjusted to the F2 generation. Heritability estimates of culm length, heading date, and mean grain weight from two populations of F6 families, each derived from a single F5 plant, were computed using this formula, and a formula which estimates the value of the genetic variance from the phenotypic variance in the Fn generation (“Fn estimates”). The FN h2 estimates at F6 were always higher than those adjusted to F2 variance, due to the increase in additive variance and the reduction in dominance variance.

GENETIC VARIANCES IN AN EIGHT PARENT HALF DIALLEL OF OATS

1976 ◽  
Vol 18 (3) ◽  
pp. 419-427 ◽  
Author(s):  
D. R. Sampson ◽  
I. Tarumoto
Keyword(s):  
Grain Yield ◽  
Genetic Variance ◽  
Additive Genetic Variance ◽  
Heading Date ◽  
Phenotypic Variance ◽  
Narrow Sense ◽  
Narrow Sense Heritability ◽  
Additive Component ◽  
Tests Of Fit ◽  
Half Diallel

Twenty-eight progenies with their eight parent cultivars of Avena saliva L. (2n = 6x = 42) were grown in F1, F2 and F3 in separate years; the F1 as spaced plants, the F2 and F3 as dense seeded populations. Additive genetic variance constituted most of the phenotypic variance of eight traits (heading date, plant height, stem diameter, grain yield and four components of yield) according to a Griffing Method 4, Model II analysis. Similarly, additive × year interactions were more important than nonadditive × year interactions. A Hayman-Jinks analysis of the same material but with the parents included showed that the additive component was 2 to 16 times larger than the dominance components in the F1 However in the F2 and F3 the dominance components became larger than the additive components for most traits instead of declining in importance as expected. Further, tests of fit to the hypotheses underlying the Hayman-Jinks analysis were negative in 8 of 24 cases. It is postulated that these discrepancies result from epistatic variance which caused an upward bias in the dominance estimates. The calculation and uses of two estimates of narrow-sense heritability are discussed.

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