Relative fitnesses of the four phenotypes.

The relative fitness of individuals carrying the T trait can differ from that of individuals carrying the t trait. The amount of this difference is dictated by the N state: the N trait confers a fitness difference of σ1 between TN and tN, and the n trait confers a fitness difference of σ2 between Tn and tn.

携带T性状的个体的相对适合度，与携带t性状的个体的相对适合度可能存在差异。该差异的大小由N状态决定：当个体携带N性状时，TN与tN个体间的适合度差异为σ₁；当个体携带n性状时，Tn与tn个体间的适合度差异为σ₂。