Skip to main content
×
Home
    • Aa
    • Aa

Associative overdominance caused by linked detrimental mutations*

  • Tomoko Ohta (a1)
Summary
SUMMARY

Associative overdominance due to linked detrimental mutations was investigated using the method of moment equations based on diffusion models. The expectation of the apparent selective value at the marker (neutral) locus has been evaluated. Assume two linked loci, at one of which the steady flux equilibrium is reached under constant mutational input of deleterious mutations (with rate v) having disadvantages hs in heterozygote and s in homozygotes. At another locus, the neutral alleles are segregating with frequencies near 0·5. Let Ne be the effective size of the population and c be the recombination fraction between the two loci. Then the coefficient of associative overdominance at the neutral locus can be obtained by taking the expectation with respect to chromosome frequencies at steady flux equilibrium. It becomes approximately

where (LI−L0) is the inbreeding depression caused by deleterious mutations under complete inbreeding, and Nehs ≫ l and hsv are assumed. More generally, if the inbreeding depression of a chromosome segment with a length of recombination fraction C is (LI−L0) then s′ at the neutral marker at the edge of the segment is

where hs is the average heterozygote disadvantage of detrimentals.

The significance of the associative overdominance is discussed in relation to actual observations. It is proposed that the most of the observed heterozygote superiority including inversion chromosomes of Drosophila, isozyme alleles in Avena and ABO blood group genes in man could be explained by the associated detrimentals.

Copyright
References
Hide All
Chung C. S., Matsunaga E. & Morton N. E. (1960). The ABO polymorphism in Japan. Japanese Journal of Human Genetics 5, 124134.
Crow J. F. (1968). Some analysis of hidden variability in Drosophila populations. In Population Biology and Evolution, ed. Lewontin R. C., pp. 7186. New York: Syracuse, Syracuse University Press.
Chow J. F. & Temin R. G. (1964). Evidence for the partial dominance of recessive lethal genes in natural populations of Drosophila. American Naturalist 98, 2133.
Latter B. D. H. & Robertson A. (1962). The effects of inbreeding and artificial selection on reproductive fitness. Genetical Research 3, 110138.
Kimura M. & Ohta T. (1969 a). The average number of generations until fixation of a mutant gene in a finite population. Genetics 61, 763771.
Kimura M. & Ohta T. (1969 b). The average number of generations until extinction of an individual mutant gene in a finite population. Genetics 63, 701709.
Kimura M. & Ohta T. (1971). Theoretical Aspects of Population Genetics. Princeton University Press, (in the Press).
Marshall D. R. & Allard R. W. (1970). Maintenance of isozyme polymorphisms in natural populations of Avena barbata. Genetics 66, 393399.
Nei M. (1968). The frequency distribution of lethal chromosomes in finite populations. Proceedings of the National Academy of Sciences, U.S.A. 60, 517524.
Ohta T. (1971). Linkage disequilibrium and associative overdominance due to random genetic drift. Japanese Journal of Genetics 49, 195206.
Ohta T. & Kimura M. (1969). Linkage disequilibrium due to random genetic drift. Genetical Research 13, 4755.
Ohta T. & Kimura M. (1970). Development of associative overdominance through linkage disequilibrium in finite populations. Genetical Research 16, 165177.
Ohta T. & Kimura M. (1971 a). Linkage disequilibrium between two segregating nucleotide sites under steady flux of mutations in finite populations. Genetics (in the Press).
Ohta T. & Kimura M. (1971 b). Behavior of neutral mutants influenced by associated over-dominant loci in finite populations. Genetics (in the Press).
Sved J. A. & Ayala F. J. (1970). A population cage test for heterosis in Drosophila pseudoobscura. Genetics 66, 97113.
Temin R. G., Meyer H. U., Dawson P. S. & Crow J. F. (1969). The influence of epistasis on homozygous viability depression in Drosophila melanogaster. Genetics 61, 497519.
Wright S. & Dobzhansky Th. (1946). Genetics of natural populations. XII. Experimental reproduction of some of the changes caused by natural selection in certain populations of Drosophila pseudoobscura. Genetics 31, 125156.
Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Genetics Research
  • ISSN: 0016-6723
  • EISSN: 1469-5073
  • URL: /core/journals/genetics-research
Please enter your name
Please enter a valid email address
Who would you like to send this to? *
×

Metrics

Full text views

Total number of HTML views: 0
Total number of PDF views: 22 *
Loading metrics...

Abstract views

Total abstract views: 103 *
Loading metrics...

* Views captured on Cambridge Core between September 2016 - 22nd October 2017. This data will be updated every 24 hours.