Journal of Genetics

, 32:375

The amount of heterozygosis to be expected in an approximately pure line

  • J. B. S. Haldane

DOI: 10.1007/BF02982522

Cite this article as:
Haldane, J.B.S. Journ. of Genetics (1936) 32: 375. doi:10.1007/BF02982522


Heterozygosis in an approximately pure line is due to two causes. On the one hand, part of the heterozygosis of the original ancestors remains for some generations. Owing to linkage a few zygotes may have comparatively large heterozygous segments, but most of them are completely homozygous. Thus it is calculated that in maize after 20 generations of self-fertilisation all but about 1 plant in 2500 is fully homozygous, but the average length of chromosome heterozygous in the exceptional plants is 2·5 units.

A fraction of the heterozygosis is due to mutation. The frequency of heterozygosis in a locus is equal to the mutation rate multiplied by a factor varying from 2 to 38 in the different breeding systems considered.

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© Indian Academy of Sciences 1936

Authors and Affiliations

  • J. B. S. Haldane

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