Figure 1
From: Reinforcement of genetic coherence in a two-locus model

Schematic representation of the model determinants of reproduction and survival: (1) gametes encounter at random, (2) gamete fusion is determined by the B-locus (the object locus of mating), and fusion probabilities are modified by the A-locus (the mating modifier locus), (3) survival is determined by the B-locus (the object locus of survival) only; the B-locus thus is object of both gamete fusion and survival. The framed part refers to differential fusion modification with respect to homotypic and heterotypic encounters at the object locus B.