Figure 2.

Resolution of sexual and parental antagonism. (A) The optimal level of expression in males is M* and in females F*. Sex expression is initially the same in both sexes at a compromise between their respective optima (green dot). Sex-specific expression allows M* to be achieved in males and F* in females (red dot). (B) The optimal level of expression for patrigenes is p* and for matrigenes m* (in this example, m* > p*). The blue line represents all combinations of matrigenic and patrigenic expression that sum to p* and the reddish line represents all combinations that sum to m*. Gene expression is initially unimprinted at a compromise between m* and p* (green dot). Imprinted expression allows silencing of the patrigenic allele and expression of m* by the matrigenic allele (red dot).