scholarly journals Variance component analysis for viability in an isolated population of Drosophila melanogaster

1983 ◽  
Vol 42 (2) ◽  
pp. 207-217 ◽  
Author(s):  
Hidenori Tachida ◽  
Muneo Matsuda ◽  
Shin-Ichi Kusakabe ◽  
Terumi Mukai
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Variance ◽  
Balancing Selection ◽  
Additive Genetic Variance ◽  
Diallel Cross ◽  
Variance Component Analysis ◽  
Logarithmic Scale ◽  
Dominance Variance ◽  
Diversifying Selection ◽  
Partial Diallel

SUMMARYUsing the 602 second chromosome lines extracted from the Ishigakijima population of Drosophila melanogaster in Japan, partial diallel cross experiments (Design II of Comstock & Robinson, 1952) were carried out, and the additive genetic variance and the dominance variance of viability were estimated. The estimated value of the additive genetic variance is 0·01754±0·00608, and the dominance variance 0·00151±0·00114, using a logarithmic scale. Since the value of the additive genetic variance is much larger than expected under mutation–selection balance although the dominance variance is compatible with it, we speculate that in the Ishigakijima population some type of balancing selection must be operating to maintain the genetic variability with respect to viability at a minority of loci. As candidates for such selection, overdominance, frequency-dependent selection, and diversifying selection are considered, and it is suggested that diversifying selection is the most probable candidate for increasing the additive genetic variance.

scholarly journals THE GENETIC VARIANCE FOR VIABILITY AND ITS COMPONENTS IN A LOCAL POPULATION OF DROSOPHILA MELANOGASTER

Genetics ◽  
1974 ◽  
Vol 78 (4) ◽  
pp. 1195-1208
Author(s):  
Terumi Mukai ◽  
Ricardo A Cardellino ◽  
Takao K Watanabe ◽  
James F Crow
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Parameters ◽  
Genetic Variance ◽  
Polymorphic Locus ◽  
Local Population ◽  
Diallel Cross ◽  
Actual Number ◽  
Additive Variance ◽  
Selection For ◽  
Partial Diallel

ABSTRACT Two hundred and ninety second chromosomes extracted from a natural population of Drosophila melanogaster were analyzed to estimate the genetic variance of viability and its components by means of a partial diallel cross (Design II of Comstock and Robinson 1952). The additive and dominance variances are estimated to be 0.009 and 0.0012. Using the dominance variance and the inbreeding depression, the effective number of overdominant loci contributing to the variance in viability is estimated to be very small, a dozen or less. Either the actual number of loci is small, or the distribution of viabilities is strongly skewed with a large majority of very weakly selected loci. The additive variance in viability appears to be too large to be accounted for by recurrent harmful mutants or by overdominant loci at equilibrium with various genetic parameters estimated independently. The excess might be due to frequency-dependent selection, to negative correlations between viability and fertility, or possibly to the presence of a mutator. The selection for viability and fertility, or possibly to the presence of a mutator. The selection for viability at the average polymorphic locus must be very slight, of the order of 10-3 or less.

scholarly journals The Genetic Structure of Natural Populations of Drosophila melanogaster. XX. Comparison of Genotype-Environment Interaction in Viability Between a Northern and a Southern Population

Genetics ◽  
1987 ◽  
Vol 117 (2) ◽  
pp. 245-254
Author(s):  
Toshiyuki Takano ◽  
Shinichi Kusakabe ◽  
Terumi Mukai
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Variance ◽  
Additive Genetic Variance ◽  
Natural Populations ◽  
Environment Interaction ◽  
Southern Population ◽  
Genotypic Variance ◽  
Diversifying Selection ◽  
Genotype Environment Interaction ◽  
Interaction Variance

ABSTRACT In order to examine the operation of diversifying selection as the maintenance mechanism of excessive additive genetic variance for viability in southern populations in comparison with northern populations of Drosophila melanogaster, two sets of experiments were conducted using second chromosomes extracted from the Ogasawara population (a southern population in Japan) and from the Aomori population (a northern population in Japan). Chromosomal homozygote and heterozygote viabilities were estimated in eight kinds of artificially produced breeding environments. The main findings in the present investigation are as follows: (1) Significant genotype-environment interaction was observed using chromosomes extracted from the Ogasawara population. Indeed, the estimate of the genotype-environment interaction variance for heterozygotes was significantly larger than that of the genotypic variance. On the other hand, when chromosomes sampled from the Aomori population were examined, that interaction variance was significant only for homozygotes and its value was no more than one quarter of that for the chromosomes from the Ogasawara population. (2) The average genetic correlation between any two viabilities of the same lines estimated in the eight kinds of breeding environments for the chromosomes sampled from the Ogasawara population was smaller than that for the chromosomes from the Aomori population both in homozygotes and in heterozygotes, especially in the latter. (3) The stability of heterozygotes over homozygotes against fluctuations of environmental conditions was seen in the chromosomes from the Ogasawara population, but not from the Aomori population. (4) From the excessive genotype-environment interaction variance compared with the genotypic variance in heterozygotes, it was suggested for the chromosomes from the Ogasawara population that the reversal of viability order between homozygotes took place in some environments at the locus level. On the basis of these findings, it is strongly suggested that diversifying selection is operating in a southern population of D. melanogaster on some of the viability polygenes which are probably located outside the structural loci, and the excessive additive genetic variance of viability in southern populations is maintained by this type of selection.

THE GENETIC STRUCTURE OF NATURAL POPULATIONS OF DROSOPHILA MELANOGASTER. XIX. GENOTYPE-ENVIRONMENT INTERACTION IN VIABILITY

Genetics ◽  
1985 ◽  
Vol 111 (1) ◽  
pp. 43-55
Author(s):  
Hidenori Tachida ◽  
Terumi Mukai
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Variance ◽  
Culture Media ◽  
Additive Genetic Variance ◽  
Natural Populations ◽  
Environment Interaction ◽  
Diversifying Selection ◽  
Genotype Environment Interaction ◽  
Significant Difference ◽  
Experimental Findings

ABSTRACT To investigate whether or not an excess of additive genetic variance for viability detected in southern natural populations of Drosophila melanogaster was created by diversifying selection, genotype-environment interaction was tested as follows. (1) Two karyotype chromosomes were used: 61 second chromosomes with the standard karyotype and 63 second chromosomes carrying In(2L)t. Their homozygote viabilities were larger than 50% of the average viability of random heterozygotes. (2) The effects of two factors (culture media and yeasts) were examined at three levels (the culture media: tomato, corn and banana; and the yeasts: sake, brewer's and baker's). The results of 16 three by three factorial experiments by the Cy method in the same karyotype groups for relative viabilities of homozygotes and heterozygotes elucidated the following findings: (1) there was no significant difference between the two karyotype groups, (2) the variance components of genotype-environment interaction were highly significant, (3) the variance component of heterozygotes was significantly smaller than that of homozygotes. From the experimental findings and previous results, diversifying selection in natural populations acting on viability polygenes to increase the additive genetic variance was suggested. The relation of the present result to protein polymorphism is also discussed.

scholarly journals Effects of stress combinations on the expression of additive genetic variation for fecundity in Drosophila melanogaster

1998 ◽  
Vol 72 (1) ◽  
pp. 13-18 ◽  
Author(s):  
CARLA M. SGRÒ ◽  
ARY A. HOFFMANN
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Variance ◽  
Cold Shock ◽  
Additive Genetic Variance ◽  
Combined Stress ◽  
Heritable Variation ◽  
Environmental Variance ◽  
Apparent Increase ◽  
Nutrition Environment ◽  
Stress Combinations

To test whether stressful conditions altered levels of heritable variation in fecundity in Drosophila melanogaster, parent–offspring comparisons were undertaken across three generations for flies reared in a combined stress (ethanol, cold shock, low nutrition) environment or a control environment. The stressful conditions did not directly influence fecundity but did lead to a reduced fecundity in the offspring generations, perhaps reflecting cross-generation maternal effects. Both the heritability and evolvability estimates were higher in the combined stress treatment, reflecting an apparent increase in the additive genetic variance under stress. In contrast, there were no consistent changes in the environmental variance across environments.

scholarly journals Variance Component Analysis of Parthenocarpic Character in a Processing Cucumber (Cucumis sativus L.) population

HortScience ◽  
2004 ◽  
Vol 39 (4) ◽  
pp. 881A-881
Author(s):  
Zhanyong Sun* ◽  
Richard L. Lower ◽  
Jack E. Staub
Keyword(s):  
Cucumis Sativus ◽  
Variance Component ◽  
Genetic Variance ◽  
Additive Genetic Variance ◽  
Component Analysis ◽  
Variance Component Analysis ◽  
Individual Plant ◽  
Normal Leaf ◽  
Dominance Genetic Variance ◽  
Plant Basis

The incorporation of genes for parthenocarpy (production of fruit without fertilization) has potential for increasing yield in pickling cucumber (Cucumis sativus L.). The inheritance of parthenocarpy in cucumber is not well understood, and thus a genetic analysis was performed on F3 cross-progeny resulting from a mating between the processing cucumber inbred line 2A (P1, gynoecious, parthenocarpic, indeterminate, normal leaf) and Gy8 (P2, gynoecious, non-parthenocarpic, indeterminate, normal leaf). A variance component analysis was performed to fruit yield data collected at two locations (designated E-block and G-block) at Hancock, WI in 2000. The relative importance of additive genetic variance compared to dominance genetic variance changed across environments. The additive genetic variance was 0.5 and 4.3 times of dominance genetic variance in E-block and G-block, respectively. The estimated environmental variance accounted for ≈90% of the total phenotypic variance on an individual plant basis in both locations. Narrow-sense heritability estimated on an individual plant basis ranged from 0.04 (E-block) to 0.12 (G-block). Broad-sense heritability estimated on an individual plant basis ranged from 0.12 (E-block) to 0.15 (G-block). The minimum number of effective factors controlling parthenocarpy was estimated to range between 5 (G-block) to 13 (E-block). These results suggest that the response to direct selection of individual plants for improving parthenocarpy character will likely be slow and difficult. Experiment procedures that minimize the effect of environment on the expression of parthenocarpy will likely maximize the likelihood of gain from selection.

scholarly journals Autosomal and X-Linked Additive Genetic Variation for Lifespan and Aging: Comparisons Within and Between the Sexes in Drosophila melanogaster

2016 ◽  
Vol 6 (12) ◽  
pp. 3903-3911 ◽  
Author(s):  
Robert M Griffin ◽  
Holger Schielzeth ◽  
Urban Friberg
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Variation ◽  
X Chromosome ◽  
Dosage Compensation ◽  
Genetic Variance ◽  
Additive Genetic Variance ◽  
Conclusive Evidence ◽  
Substitution Lines ◽  
Chromosome Substitution Lines ◽  
Sexually Antagonistic Selection

Abstract Theory makes several predictions concerning differences in genetic variation between the X chromosome and the autosomes due to male X hemizygosity. The X chromosome should: (i) typically show relatively less standing genetic variation than the autosomes, (ii) exhibit more variation in males compared to females because of dosage compensation, and (iii) potentially be enriched with sex-specific genetic variation. Here, we address each of these predictions for lifespan and aging in Drosophila melanogaster. To achieve unbiased estimates of X and autosomal additive genetic variance, we use 80 chromosome substitution lines; 40 for the X chromosome and 40 combining the two major autosomes, which we assay for sex-specific and cross-sex genetic (co)variation. We find significant X and autosomal additive genetic variance for both traits in both sexes (with reservation for X-linked variation of aging in females), but no conclusive evidence for depletion of X-linked variation (measured through females). Males display more X-linked variation for lifespan than females, but it is unclear if this is due to dosage compensation since also autosomal variation is larger in males. Finally, our results suggest that the X chromosome is enriched for sex-specific genetic variation in lifespan but results were less conclusive for aging overall. Collectively, these results suggest that the X chromosome has reduced capacity to respond to sexually concordant selection on lifespan from standing genetic variation, while its ability to respond to sexually antagonistic selection may be augmented.

Estimation of additive and dominance genetic variance components for female fertility traits in Iranian Holstein cows

2018 ◽  
Vol 156 (4) ◽  
pp. 565-569
Author(s):  
H. Ghiasi ◽  
R. Abdollahi-Arpanahi ◽  
M. Razmkabir ◽  
M. Khaldari ◽  
R. Taherkhani
Keyword(s):  
Dairy Cows ◽  
Variance Components ◽  
Genetic Variance ◽  
Additive Genetic Variance ◽  
Genetic Effects ◽  
Information Criteria ◽  
Phenotypic Variance ◽  
Dominance Variance ◽  
Dominance Genetic Variance ◽  
Estimated Heritability

AbstractThe aim of the current study was to estimate additive and dominance genetic variance components for days from calving to first service (DFS), a number of services to conception (NSC) and days open (DO). Data consisted of 25 518 fertility records from first parity dairy cows collected from 15 large Holstein herds of Iran. To estimate the variance components, two models, one including only additive genetic effects and another fitting both additive and dominance genetic effects together, were used. The additive and dominance relationship matrices were constructed using pedigree data. The estimated heritability for DFS, NSC and DO were 0.068, 0.035 and 0.067, respectively. The differences between estimated heritability using the additive genetic and additive-dominance genetic models were negligible regardless of the trait under study. The estimated dominance variance was larger than the estimated additive genetic variance. The ratio of dominance variance to phenotypic variance was 0.260, 0.231 and 0.196 for DFS, NSC and DO, respectively. Akaike's information criteria indicated that the model fitting both additive and dominance genetic effects is the best model for analysing DFS, NSC and DO. Spearman's rank correlations between the predicted breeding values (BV) from additive and additive-dominance models were high (0.99). Therefore, ranking of the animals based on predicted BVs was the same in both models. The results of the current study confirmed the importance of taking dominance variance into account in the genetic evaluation of dairy cows.

scholarly journals Combining ability study in waterlogged tolerant maize (Zea mays L.)

2014 ◽  
Vol 39 (2) ◽  
pp. 283-291 ◽  
Author(s):  
MN Amin ◽  
M Amiruzzaman ◽  
A Ahmed ◽  
MR Ali
Keyword(s):  
Combining Ability ◽  
Genetic Variance ◽  
Zea Mays L ◽  
Additive Genetic Variance ◽  
Diallel Cross ◽  
Kernel Weight ◽  
Hybrid Variety ◽  
Additive Gene ◽  
Ear Height ◽  
Kernel Yield

Combining ability was studied for kernel yield and yield components in a 8×8 diallel cross of waterlogged tolerant maize. Significant general and specific combining ability variances were observed for all the characters studied. Additive genetic variance was preponderant in plant height, ear height, ear length, ear diameter, and kernel weight and non-additive gene action was involved in days to silking, number of kernels per ear and kernel yield. The parental lines E-31 and E-79 were found to be the best general combiners for yield. The good combining parents for different traits could be used in hybridization to improve yield and other desirable traits as donor parents for the accumulation of favourable genes. The cross combinations, E 31× E 40, E 31× E 64, E 31× E 79, E 38× E 40, E 58× E 79, E 63× E 79, E 64 × E 79 showing significant and positive sca effects can be used for commercial hybrid variety development after verifying them at different locations. DOI: http://dx.doi.org/10.3329/bjar.v39i2.20430 Bangladesh J. Agril. Res. 39(2): 283-291, June 2014

scholarly journals Quantitative genetics of postponed aging in Drosophila melanogaster. II. Analysis of selected lines.

Genetics ◽  
1991 ◽  
Vol 127 (4) ◽  
pp. 729-737
Author(s):  
E W Hutchinson ◽  
A J Shaw ◽  
M R Rose
Keyword(s):  
Drosophila Melanogaster ◽  
Maternal Effects ◽  
Genetic Variance ◽  
Additive Genetic Variance ◽  
Starvation Resistance ◽  
Selected Lines ◽  
Quantitative Genetic ◽  
Degree Of Differentiation ◽  
Postponed Aging ◽  
Allelic Differentiation

Abstract Quantitative genetic analyses of Drosophila melanogaster stocks with postponed aging have suffered from the problem of a lack of certainty concerning patterns of allelic differentiation. The present experiments were designed to alleviate this difficulty by selecting for enhanced levels of characters known to be related to postponed aging. Selection successfully increased the degree of differentiation of postponed aging stocks with respect to starvation resistance and fecundity, but persistent additive genetic variance suggested that selection did not result in fixation of alleles. The artificially selected stocks were subjected to crosses to test for patterns of dominance and maternal effects. There was little evidence for these effects in the inheritance of the characters underlying postponed aging, even with the increased differentiation of the selected stocks.

The Changes in Genetic and Environmental Variance With Inbreeding in Drosophila melanogaster

Genetics ◽  
1999 ◽  
Vol 152 (1) ◽  
pp. 345-353 ◽  
Author(s):  
Michael C Whitlock ◽  
Kevin Fowler
Keyword(s):  
Drosophila Melanogaster ◽  
Large Scale ◽  
Genetic Variance ◽  
Additive Genetic Variance ◽  
Inbred Lines ◽  
Residual Variance ◽  
Phenotypic Variance ◽  
Population Bottlenecks ◽  
Environmental Variance ◽  
Components Of Variance

Abstract We performed a large-scale experiment on the effects of inbreeding and population bottlenecks on the additive genetic and environmental variance for morphological traits in Drosophila melanogaster. Fifty-two inbred lines were created from the progeny of single pairs, and 90 parent-offspring families on average were measured in each of these lines for six wing size and shape traits, as well as 1945 families from the outbred population from which the lines were derived. The amount of additive genetic variance has been observed to increase after such population bottlenecks in other studies; in contrast here the mean change in additive genetic variance was in very good agreement with classical additive theory, decreasing proportionally to the inbreeding coefficient of the lines. The residual, probably environmental, variance increased on average after inbreeding. Both components of variance were highly variable among inbred lines, with increases and decreases recorded for both. The variance among lines in the residual variance provides some evidence for a genetic basis of developmental stability. Changes in the phenotypic variance of these traits are largely due to changes in the genetic variance.

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