Variations in the Transmission Ratios of Alleles Through Egg and Sperm in Mus musculus

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Abstract
Evidence is reviewed from breeding experiments showing that the same mutant t-alleles which are transmitted in normal ratios (.5) by heterozygous females are transmitted in a variety of ratios (.99 to .35) by males heterozygous for different alleles. Of 37 alleles tested, 22 lethals all gave abnormal ratios (20 high, 2 low); of 15 viable alleles 3 gave high, 9 gave normal and 3 low ratios. 18 alleles found in different wild populations all gave high ratios; 19 alleles observed at origin in the laboratory by mutation (probably involving rare events of recombination) gave ratios covering the whole gamut from .99 to .35. It is concluded that the former are a selected sample of the latter, only those alleles being retained in populations which are favored by very high transmission ratios. The mechanism by which abnormal transmission ratios are produced is discussed in terms of an hypothesis, proposed by Braden, which assumes that the success of a sperm in effecting fertilization is influenced by the allele which it contains. Only certain alleles express this property. This physiological hypothesis has not yet been fully tested.