scholarly journals ESTIMATION OF GENETIC VARIANCE COMPONENTS AND IDENTIFICATION OF TRANSGRESSIVE SEGREGANTS FOR TWO INTRASPECIFIC EXTRA-LONG STAPLE COTTON CROSSES

2021 ◽  
Vol 6 (1) ◽  
pp. 53-70
Author(s):  
Reham H. A. O. Gibely
Keyword(s):  
Variance Components ◽  
Genetic Variance ◽  
Transgressive Segregants

Genetic variance components for female fertility in Iranian Holstein cows

2011 ◽  
Vol 139 (3) ◽  
pp. 277-280 ◽  
Author(s):  
Heydar Ghiasi ◽  
Abbas Pakdel ◽  
Ardeshir Nejati-Javaremi ◽  
Hassan Mehrabani-Yeganeh ◽  
Mahmood Honarvar ◽  
...  
Keyword(s):  
Variance Components ◽  
Genetic Variance ◽  
Female Fertility ◽  
Holstein Cows

scholarly journals Genetic analysis of spike traits in two- and multi-rowed barley crosses

Genetika ◽  
2012 ◽  
Vol 44 (3) ◽  
pp. 475-482
Author(s):  
Milomirka Madic ◽  
Desimir Knezevic ◽  
Aleksandar Paunovic ◽  
Dragan Djurovic
Keyword(s):  
Variance Components ◽  
Genetic Variance ◽  
Grain Weight ◽  
Spike Length ◽  
Grain Number ◽  
Partial Dominance ◽  
Grain Number Per Spike ◽  
Diallel Crossing ◽  
Barley Genotypes ◽  
Mode Of Inheritance

Mode of inheritance and genetic variance components for spike length, grain number per spike and grain weight per spike were evaluated in four parental genotypes and their F1 and F2 hybrids obtained through incomplete diallel crossing. Multi-rowed barley genotypes HVW-247 and Partizan and two-rowed barley genotypes KG-15 and NS-293 were selected for the crossing based on the trait concept with the parents being divergent for spike length, grain number per spike and grain weight per spike. The average values for spike length in F1 and F2 generations were intermediate or close to those of the parent having longer spikes, with the mode of inheritance being partial dominance, dominance or overdominance, depending on the crossing combination. The six-rowed x six-rowed and two-rowed x two-rowed crossing combinations showed dominance of increased grain number per spike and increased grain weight per spike in the inheritance of grain number per spike and grain weight per spike, respectively, whereas the six-rowed x two-rowed cross was predominated by partial dominance.

scholarly journals Quantitative genetics and the evolution of ontogeny: I. Ontogenetic changes in quantitative genetic variance components in randombred mice

1983 ◽  
Vol 42 (1) ◽  
pp. 65-75 ◽  
Author(s):  
James M. Cheverud ◽  
Larry J. Leamy ◽  
William R. Atchley ◽  
J. J. Rutledge
Keyword(s):  
Maternal Effects ◽  
Environmental Effects ◽  
Variance Components ◽  
Genetic Variance ◽  
Tail Length ◽  
Head Length ◽  
Ontogenetic Changes ◽  
Trunk Length ◽  
Quantitative Genetic ◽  
Significant Difference

SUMMARYWe report the results of an ontogenetic analysis of quantitative genetic variance components with two replicates drawn from the randombred ICR strain of mice. A total of 432 mice from 108 full-sib families raised in a cross-fostering design were used to estimate direct effects heritability, maternal effects, and environmental effects for weight, head length, trunk length, trunk circumference, and tail length at 17, 24, 31, 38, 45, 52, 59, and 66 days of age. There was no significant difference in heritability between the replicates. Heritabilities either stayed more or less constant with age at about 0·30 (weight, trunk length, trunk circumference) or increased slightly with age (head length, tail length). Maternal effects decreased with age from a maximum of about 0·50 at weaning to about 0·15 at age 66 when growth was nearly complete. Environmental effects increased in relative importance during ontogeny.

What contributes to differences in phenotypic variation between generations?

2009 ◽  
Vol 2009 ◽  
pp. 200-200
Author(s):  
A Wolc ◽  
I White ◽  
M Lisowski ◽  
W G Hill
Keyword(s):  
Animal Model ◽  
Environmental Effects ◽  
Environmental Conditions ◽  
Phenotypic Variation ◽  
Variance Components ◽  
Genetic Variance ◽  
Phenotypic Variance ◽  
Base Population ◽  
Substantial Heterogeneity ◽  
Over Time

Under the animal model genetic variance is estimated in the base population taking into account inbreeding and is otherwise assumed to remain unchanged over generations. In practice, phenotypic variation differs randomly or systematically over time. Intuitively, such changes would be attributed mostly to environmental effects, and so lower heritability would be expected when variation is inflated. Studies in dairy cattle show contradictory results (e.g. Boldman and Freeman, 1990). Laying hens are kept under environmental conditions intended to be constant, but show substantial heterogeneity in phenotypic variance (VP) over generations. The aim was to investigate how variance components change.

Comparison of F2 and F∞ diallel analyses in barley

Genome ◽  
1988 ◽  
Vol 30 (6) ◽  
pp. 865-869 ◽  
Author(s):  
T. M. Choo ◽  
E. Reinbergs ◽  
P. Y. Jui
Keyword(s):  
Hordeum Vulgare ◽  
Grain Yield ◽  
Plant Height ◽  
Variance Components ◽  
Genetic Variance ◽  
Additive Genetic Variance ◽  
Heading Date ◽  
Diallel Analysis ◽  
Hordeum Vulgare L ◽  
Hill Plots

A study was conducted in barley (Hordeum vulgare L.) to compare the relative magnitudes of heterosis to additive × additive epistasis and to compare F2 and F∞, diallel analyses. Both F2 and F∞, progenies were derived from 7 × 7 diallel crosses. Progenies and their parents were evaluated for grain yield, heading date, plant height, and the number of spikes per hill in hill plots with five replications at Elora (Ontario) in 1978. Results suggested that additive × additive epistasis were present for these traits and its magnitude was similar to that of heterosis estimated in F2. Both F2 and F∞ analyses detected the presence of epistasis. Both analyses provided similar estimates of the additive genetic variance for heading date and the number of spikes per hill, but the F2 analysis provided higher estimates than the F∞ analysis for grain yield and plant height. The estimate for grain yield and plant height obtained from the F2 analysis could be biased upward because of the invalid assumption of no epistasis. Estimates of other genetic variance components from the F2 analysis could be biased also. The F∞ diallel analysis not only provided estimates of additive × additive genetic variance for the four traits, it also allowed detection of nonindependent gene distribution in the parents for three of the four traits. Therefore, the limitations of the F2 diallel analysis in the presence of epistasis were apparent in the study. The F2 diallel analysis, however, could be used to detect dominance and maternal effects and thus to complement the F∞ diallel analysisKey words: barley, Hordeum vulgare, diallels, haploids, epistasis, heterosis.

Studies on Combining Ability for Seed Yield and Its Related Traits in Blackgram [Vigna mungo (L.) Hepper]

2020 ◽  
Author(s):  
Ranjana Patial ◽  
R. K. Mittal ◽  
V. K. Sood ◽  
Shahnawaz Ahmed
Keyword(s):  
Seed Yield ◽  
Combining Ability ◽  
Genetic Variance ◽  
Gene Action ◽  
Specific Combining Ability ◽  
Breeding Programme ◽  
Plant Seed ◽  
Ability Estimates ◽  
Additive Gene ◽  
Transgressive Segregants

An experiment was carried out in blackgram using line x tester mating design to estimate the GCA effect of parents and SCA effect of 54 hybrids for yield and its traits using 27 lines and two testers. The relative estimates of variance due to specific combining ability (SCA) were higher than general combining ability (GCA) variances for all twelve traits, indicating predominance of non-additive gene action. Combining ability estimates showed significant genetic variance in lines for all traits whereas testers had significant genetic variance for nine traits. On the basis of GCA effects, among the lines and testers IC-436910, IC-413306, IC-398973, IC-343885 and HPBU-111 respectively, were good combiners for most of the traits and can be used in future breeding programme. Specific combining ability studies indicated cross IC-436910 x HPBU-111 as best specific combiner for the economically important traits viz., plant height, branches per plant, seed yield per plant and days to 75% maturity. Such crosses could be further exploited to obtain transgressive segregants in future breeding programme.

Quantitative inheritance studies in sugar-cane. I. Estimation of variance components

1971 ◽  
Vol 22 (1) ◽  
pp. 93 ◽  
Author(s):  
DM Hogarth
Keyword(s):  
Factorial Design ◽  
Variance Components ◽  
Genetic Variance ◽  
Additive Genetic Variance ◽  
The Other ◽  
Quantitative Inheritance ◽  
Genetic Determination ◽  
Nested Design ◽  
Dominance Genetic Variance ◽  
Estimation Of Variance

Two experiments in quantitative genetics were conducted, one based on a nested design in lattice squares and the other on a factorial design in a balanced lattice. Lattice designs were found to be suitable for genetic experiments if a large number of crosses was involved, but posed some problems in partitioning the sum of squares for treatments. The factorial design was considered preferable to the nested design, although neither design permitted estimation of epistatic variances which, therefore, were assumed to be negligible. Additive genetic variance was found to be more important than dominance genetic variance for most characters. However, most estimates of genetic variance lacked precision in spite of the use of large, precise experiments, which illustrated the difficulty in obtaining estimates of variance components with adequate precision. The validity of assumptions made for these analyses is discussed. The effect of competition was studied and estimates of heritability and degree of genetic determination were determined.

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