Reproductive Isolation Mechanism Resulting from Resolution of Intragenomic Conflict

Crosses have revealed the species-specific, positively correlated intensities of paternally expressed growth enhancer (GE) and maternally expressed growth suppressor (GS), which serve as a reproductive isolation mechanism in many plants and animals. However, how this mechanism evolved has remained unanswered. A dynamic model shows that the conflict between paternally and maternally inherited genomes may drive them to an evolutionary "arms race" of their GE and GS productions, respectively. This results in paternally expressed GE and maternally expressed GS, and their evolutionarily stable intensities are both decreasing functions of species-specific degree of paternity and GE and GS production costs, thereby establishing a mechanism for postzygotic isolation.