Haldane's rule

English

Etymology

Formulated in 1922 by the British evolutionary biologist J. B. S. Haldane.

Proper noun

Haldane's rule

1. An observation about the early stage of speciation, stating that if in a species hybrid only one sex is inviable or sterile, that sex is more likely to be the heterogametic sex.
   • 2018, Tim Flannery, Europe: The First 100 Million Years, Penguin, published 2019, page 181:

     One study hints at the possibility that Haldane's rule may have been the cause of the lack of Neanderthal DNA on the Y-chromosome of hybrids, but currently we do not definitively know.