Fig. 5.

A schematic of the fitness of alleles within a gene for which gbM is favored by selection; i.e., a BM gene. Alleles A, B, and C are shown with circles denoting methylated cytosines within the coding region. Given that selection is on a region, alleles A and B have similar fitness effects despite detectable methylation polymorphism, because their overall methylation exceeds some threshold (vertical dashed line on the fitness graph). In contrast, allele C is undermethylated and has lower fitness.