The Hymenoptera (ants, bees, wasps and sawflies) have long been known for their haplo-diploid genetic system. As early as 1845 Dzierzon proposed for honey-bees that males arise from unfertilized eggs, females from fertilized eggs. The same principle is now thought to operate in nearly all sexual hymenopterans, many other arthropods, and some rotifers (Bac-ci, 1965; Hartl and Brown, 1970; White, 197 3). Haplo-diploidy contrasts with the more usual, diploid genetic system in three ways. One is facultative parthenogenesis. Eggs develop with or without fertilization. A second is inheritance. Males transmit only their mother's genome and transmit it only to daughters. Third, haplo-diploids may be unique in sex determination because unfertilized eggs develop as male, fertilized eggs as female (Crozier, 1971; White 197 3). The types of sex determination thought to be prevalent in diploid animals ("recessive X" or "dominant Y" mechanisms, White, 1973, p. 576) require that the two sexes differ in the sex chromosome/autosome ratio; in haplo-diploids the sexes have the same ratio. Thus White (1973, p. 683) supposed that the evolution of haplo-diploidy "obviously involves the replacement of an original sex determining mechanism by an entirely new one."
Bull, J. J., "Coevolution of Haplo-Diplody and Sex Determination in the Hymenoptera" (1981). Bu. Paper 1.
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