Should mating between members of two different species actually occur, what are the mechanisms that prevent the survival to birth of hybrids, individuals with parents from separate species?
Mechanisms that prevent the survival to birth of hybrids include: 1) gametic isolation, the state in which fertilization is prevented because of the incompatibility between of one species' female gametes and genital tract, and the other species' male sperm; 2) developmental isolation, the state in which the development of embryos resulting from cross-fertilization is irregular and ceases well before birth. Mechanisms that prevent hybrids from passing on their genetic material include: 1) hybrid inviolability, the state in which hybrids are weak, malformed, and die before being able to reproduce; 2) hybrid sterility; and 3) selective hybrid elimination, the state in which hybrids are less rigorous than parental forms and are selected against.
