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Regular responses to selection 2. Recombination and accelerated response

Published online by Cambridge University Press:  14 April 2009

J. M. Thoday
Affiliation:
University of Cambridge, Department of Genetics, Milton Road, Cambridge
J. B. Gibson
Affiliation:
University of Cambridge, Department of Genetics, Milton Road, Cambridge
S. G. Spickett
Affiliation:
University of Cambridge, Department of Genetics, Milton Road, Cambridge
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1. It has been shown that the lines dp 1, dp 2, vg 4 and vg 6 of Thoday & Boam (1961) each have two high sternopleural chaeta number genes or ‘effective factors’ between h and eyg in chromosome III. Their line dp 6 does not contain these two genes.

2. Lines derived from ancestors of dp 2 and vg 4 before the latter produced their accelerated responses have third chromosomes affecting chaeta number as if they had only one or other of these genes.

3. Of the three stocks from which all the lines derived, one, Inbred Oregon, lacks these genes. The second, vg/vg, has third chromosomes similar in effect to Oregon. The third, dp/dp, was heterogeneous, having a class of third chromosomes similar in effect to those of Oregon and a class similar to those having one high gene.

4. It is suggested that the history of the accelerated response in dp 1, dp 2 and vg 4 was as follows. Initially most of these third chromosomes were − − at the two loci, but a minority (derived from the dp/dp stock) were + − and − + (where + indicates the allele increasing chaeta number. Selection would reduce the frequency of − −, and hence increase the proportion of + −/− + heterozygotes and the probability of recombination to produce + +. Origin and multiplication of + + would account for the accelerated response.

Type
Research Article
Copyright
Copyright © Cambridge University Press 1964

References

REFERENCES

Breese, E. L. & Mather, K. (1957). The organisation of polygenic activity within a chromosome in Drosophila. I. Hair characters. Heredity, 11, 373395.CrossRefGoogle Scholar
Bridges, C. B. & Brehme, K. S. (1944). The mutants of Drosophila melanogaster. Carnegie Inst. Wash. Publ. 552.Google Scholar
Gibson, J. B. & Thoday, J. M. (1962). Effects of disruptive selection. VI. Analysis of a second chromosome polymorphism. Heredity, 17, 126.CrossRefGoogle Scholar
Mather, K. (1943). Polygenic inheritance and natural selection. Biol. Rev. 18, 3264.CrossRefGoogle Scholar
Mather, K. (1949). Biometrical Genetics. London: Methuen.Google Scholar
Spickett, S. G. (1963). Genetic and developmental studies of a quantitative character. Nature, Lond., 199, 870873.CrossRefGoogle ScholarPubMed
Thoday, J. M. (1958). The cytoplasm and quantitative variation in Drosophila. Proc. roy. Soc. B, 148, 352355.Google ScholarPubMed
Thoday, J. M. (1961). Location of polygenes. Nature, Lond., 191, 368370.CrossRefGoogle Scholar
Thoday, J. M. & Boam, T. B. (1959). Effects of disruptive selection. II. Polymorphism and divergence without isolation. Heredity, 13, 205218.CrossRefGoogle Scholar
Thoday, J. M. & Boam, T. B. (1961). Regular responses to selection. I. Description of responses. Genext. Res. 2, 161176.CrossRefGoogle Scholar
Wolstenholme, D. & Thoday, J. M. (1963). Effects of disruptive selection. VII. A third chromosome polymorphism. Heredity, 18, 413432.CrossRefGoogle ScholarPubMed