XXI.4.3.3 The higher incidence of hybrid male sterility in species with heterogametic males can be due to the fact that the production of eggs is more resistant to disturbances than the production of sperm
The hypothesis of greater robustness of oogenesis assumes that the formation of sperm is generally more sensitive to disturbances than the formation of oocytes (Hunt & Hassold 2002). It follows from experiments that, compared to the differentiation of sperm, the differentiation of oocytes more frequently progresses successfully to the end, even when the individual bears genetic defects or when this occurs under abnormal external conditions. A female with a certain genetic disorder is still fertile, while a male is not. It is possible that this is a manifestation of the general phenomenon of the greater intra-population cost of females (see XIV.7.1). Thus males can act in evolution, not only as cheap experimental material for testing new evolutionary features, but also as a “waste basket”, i.e. a means of cheap elimination of unsuitable alleles.