HALDANE’S RULE ON HYBRID STERILITY – A HYPOTHESIS FOR A MOLECULAR EXPLANATION
WOLFGANG HENNIG *
Department of Molecular and Developmental Genetics, University of Nijmegen, Toernooiveld, 6525 ED Nijmegen, The Netherlands
*Author to whom correspondence should be addressed.
Abstract
When in the F1 offspring of two different animal races one sex is absent, rare, or sterile, that sex is the heterozygous (heterogametic) sex(Haldane, 1926). This observation of J. B. S. Haldane is called Haldane's rule. Many studies have shown that Haldane's rule is generally applicable, irrespective whether the male or the female sex is heterogametic. Different the oretical explanations of this peculiar behaviour of hybrids have been promoted, though lile experimental evidence in support of one or the other hypothesis has been provided.