A new sex-ratio abnormality in Drosophila obscura

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S. Gershenson,  Genetics,  13:488. 1928.
  1. The sex-ratio in the normal lines of Drosophila obscura is very near to the theoretical 1:1.
  2. Out of 19 females caught in nature, two were heterozygous for a gene which causes strong deviations in the normal sex distribution.
  3. The researches made have shown that this gene is localized in the X-chromosome and is transmitted like an ordinary sex-linked gene.
  4. This gene is absolutely sex-limited, as it is not manifested either in heterozygous or homozygous females.
  5. The males bearing this gene give in their progeny about 96 percent of females and only about 4 percent of males.
  6. This gene has no influence on the development of the zygotes already formed, but acts directly upon the mechanism of sex-distribution. It provokes a sharp preponderance of females by almost totally removing the spermatozoa with the Y-chromosome from the fertilization process, acting thus like a gametic lethal (in the genetic sense of this term).