THE INFLUENCE OF EPISTASIS ON HOMOZYGOUS VIABILITY DEPRESSION IN <i>DROSOPHILA MELANOGASTER</i>

Temin, Rayla Greenberg; Meyer, H.U.; Dawson, Peter S.; Crow, James F.

doi:10.1093/genetics/61.2.497

Cited by 61 publications

(8 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…5007 The D: L ratio is 0.667. This figure agrees very well with the results for other populations obtained by different investigators: 0.636 by TEMIN et al (1969), and 0.584 by KOSUDA (1971) in D. melanogaster, but is slightly smaller than the value obtained in D. pseudoobscura ( D : L = 0.855) by WILLS (1966). These D: L ratios were calculated with respect to the average viability of the population.…”

Section: Heterozygotessupporting

confidence: 92%

“…It has been reported that some isozyme genes show seemingly permanent linkage disequilibria with polymorphic inversions ( MUKAI, METTLER and CHIGUSA 1971). Synergistic interactions between the second and the third chromosomes and among genes within these chromosomes have been reported in homozygous condition using D. melanogaster (TEMIN et al 1969). In the present experiment, it has been shown that the average degree of dominance of "recessive" lethal genes differs according to their genetic backgrounds.…”

Section: Overdominance and Mild Epistasismentioning

confidence: 96%

See 1 more Smart Citation

THE GENETIC STRUCTURE OF NATURAL POPULATIONS OF DROSOPHILA MELANOGASTER. XI. GENETIC VARIABILITY IN A LOCAL POPULATION

1974

View full text Add to dashboard Cite

Six hundred and ninety-one second chromosomes were extracted from a Raleigh, North Carolina population, and the following experimental results were obtained: (1) Salivary gland chromosomes of all lines were observed and the number of inversion-carrying chromosomes was 130, among which 76 carried In(2R)NS, 36 carried In(2L)t, 4 carried In(2L)t and In(2R)NS, and 14 carried different kinds of rare inversions. (2) Viabilities of homozygotes and heterozygotes were examined. The frequency of lethal-carrying chromosomes was 275/691 (or 0.398):70/130 (or 0.538) in inversion-carrying chromosomes and 205/561 (or 0.365) in inversion-free chromosomes. The former is significantly higher than the latter. The average homozygote viability was 0.4342 including lethal lines and 0.7163 excluding those, the average heterozygote viability being 1.0000. The detrimental load to lethal load ratio (D:L ratio) was 0.334/0.501 = 0.67. The average viability of lethal heterozygotes was less than that of lethal-free heterozygotes, significantly in inversion-free individuals but not significantly so in inversion-carrying individuals. Inversion heterozygotes seem to have slightly better viability than the inversion-free heterozygotes on the average, but not significantly so. (3) The average degree of dominance of viability polygenes was estimated to be 0.293 ± 0.071 for all heterozygotes whose component chromosomes had better viabilities than 0.6 of the average heterozygote viability, 0.177 ± 0.077 for inversion-free heterozygotes and 0.489 ± 0.082 for inversion heterozygotes. (4) Mutation rates of viability polygenes and lethal genes were estimated on the basis of genetic loads and average degrees of dominance of lethal genes and viability polygenes. Estimates were very close to those obtained by direct estimation. (5) Possible overdominance and epistasis were detected, but the magnitude must be very small. (6) The effective size of the population was estimated to be much greater than 10,000 by using the allelism rate of lethal-carrying chromosomes (0.0040) and their frequency.—On the basis of these findings and the comparison with the predicted result (Mukai and Maruyama 1971), the mechanisms of the maintenance of genetic variability in the population are discussed.

show abstract

Section: Heterozygotessupporting

confidence: 92%

Section: Overdominance and Mild Epistasismentioning

confidence: 96%

THE GENETIC STRUCTURE OF NATURAL POPULATIONS OF DROSOPHILA MELANOGASTER. XI. GENETIC VARIABILITY IN A LOCAL POPULATION

1974

View full text Add to dashboard Cite

show abstract

“…This is expected for reasons analogous to those for which taking only the first term of a Taylor series provides a good estimate. For the partial or complete absence of dominance in genes with small viability effects, see Greenberg & Crow (1960); for the minimum influence of epistasis, see Temin et al (1969). (Greenberg and Temin are the same person, before and after marriage.)…”

Section: Contrasting Viewsmentioning

confidence: 99%

On epistasis: why it is unimportant in polygenic directional selection

Crow

2010

Phil. Trans. R. Soc. B

143

138

View full text Add to dashboard Cite

There is a difference in viewpoint of developmental and evo-devo geneticists versus breeders and students of quantitative evolution. The former are interested in understanding the developmental process; the emphasis is on identifying genes and studying their action and interaction. Typically, the genes have individually large effects and usually show substantial dominance and epistasis. The latter group are interested in quantitative phenotypes rather than individual genes. Quantitative traits are typically determined by many genes, usually with little dominance or epistasis. Furthermore, epistatic variance has minimum effect, since the selected population soon arrives at a state in which the rate of change is given by the additive variance or covariance. Thus, the breeder's custom of ignoring epistasis usually gives a more accurate prediction than if epistatic variance were included in the formulae.

show abstract

“…We have also not taken epistasis into account. Studies of chromosomes taken from natural populations and made homozygous (TEMIN et al 1969) and of newly accumulated viability mutants (MUKAI 1969) both show evidence of slight synergism for mildly deleterious effects on viability. However, the magnitude of this epistasis is small, especially in high viability chromosomes.…”

Section: Discussionmentioning

confidence: 99%

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

et al. 1974

Self Cite

View full text Add to dashboard Cite

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.

show abstract

THE INFLUENCE OF EPISTASIS ON HOMOZYGOUS VIABILITY DEPRESSION IN DROSOPHILA MELANOGASTER

Cited by 61 publications

References 1 publication

THE GENETIC STRUCTURE OF NATURAL POPULATIONS OF DROSOPHILA MELANOGASTER. XI. GENETIC VARIABILITY IN A LOCAL POPULATION

THE GENETIC STRUCTURE OF NATURAL POPULATIONS OF DROSOPHILA MELANOGASTER. XI. GENETIC VARIABILITY IN A LOCAL POPULATION

On epistasis: why it is unimportant in polygenic directional selection

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

Contact Info

Product

Resources

About