Fig. 2.

The level of dominance of the blindness allele (h) affects the level of selection (s) required to produce blind populations. Each line represents how strong selection must be relative to migration (m) for blindness to evolve in the cave population for a given level of dominance (s ^∗/m), where s ^∗ is the minimum level of selection required for the cave population to become blind. Regions above the curves produce populations that are blind and regions below do not. Each panel contains a different condition for defining whether the cave population is blind. a For the blind allele to become the majority allele requires stronger selection when blindness is recessive (h=0) compared to when the allele for blindness is dominant. b For the blind phenotype to become the majority phenotype requires stronger selection when blindness is recessive compared to when the allele for blindness is dominant. c For the blind allele to become fixed requires stronger selection when the allele for blindness is dominant compared to when it is recessive. d For the blind phenotype to become fixed requires stronger selection when blindness is recessive. The curves were calculated analytically with u=10⁻⁶ and Q=0.01