ABSTRACT Summary Response to selection for particular rates of recombination in the silkworm (_Bombyx mori_) is rapid; from a highly heterogeneous foundation stock Hasimoto achieved, in only

10 generations, a 32 per cent difference between lines selected for high and low recombination between the dominant markers _Striped_ and _Yellow_ in chromosome 2. The present study

analyses the difference between Hasimoto’s high and low stocks by means of a set of four factorial F1 crosses, and all but one of the corresponding eight backcrosses. As there is no

recombination in females this method can distinguish the effects on recombination of (i) a large inversion in the marked chromosome (chromosome 2), (ii) genes or small inversions in

cent). At least one other autosome carries a similar gene, with _high_ recessive (effect of around 8 per cent), and there also appears to be an autosome (or several autosomes) with a _low_

recessive effect of 9 per cent, which may or may not be identical with the other autosome. Further autosomes might be revealed by a more sensitive analysis. There may be a small effect

(_high_ recessive) due to the X chromosome. There is no overall dominance in the genes controlling recombination. The genes appear to be either of the _rec_ type discovered in _Neurospora_,

or general modifiers of genomic recombination. Although supergenes in mimetic butterflies at least do not arise by the tightening of linkage between loosely linked or independent loci,

modifiers of the type demonstrated in _Bombyx_ may be very effective in tightening still further the linkage within supergenes that come into existence by the alternative “sieve“ mechanism.

If most modifiers of recombination are general in their action, rather than specific to one short length of chromosome, then this may in part explain why the genome does not congeal. SIMILAR

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references ACKNOWLEDGEMENTS Acknowledgments.-The progress of this work has been dependent on the considerable skills of Mr Mart Koello, who adapted the Japanese techniques of silkworm

rearing to our needs, and oversaw the rearing of the broods ; he is co-author of section 3. Much additional help was provided by Dr Charles Mitter, Mr Craig Sargent and Ms Melody Wolstoff.

To all these people I am extremely grateful. I am much indebted to Professor Hiroshi Doira who provided several batches of the high and low stocks from Kyushu University. The research was

supported by grant 5 ROI GM 20702 from the National Institutes of Health. AUTHOR INFORMATION Author notes * John R G Turner Present address: Department of Genetics, University of Leeds,

Leeds, LS2 9JT, England AUTHORS AND AFFILIATIONS * Department of Ecology and Evolution, State University of New York, Stony Brook, 11794, N.Y., USA John R G Turner Authors * John R G Turner

View author publications You can also search for this author inPubMed Google Scholar ADDITIONAL INFORMATION Contribution number 318 from the Program in Ecology and Evolution of the State

University of New York at Stony Brook. RIGHTS AND PERMISSIONS Reprints and permissions ABOUT THIS ARTICLE CITE THIS ARTICLE Turner, J. Genetic control of recombination in the silkworm.

_Heredity_ 43, 273–293 (1979). https://doi.org/10.1038/hdy.1979.83 Download citation * Received: 26 March 1979 * Issue Date: 01 October 1979 * DOI: https://doi.org/10.1038/hdy.1979.83 SHARE

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