In Lake Malawi Cichlid Fish, One Can Observe Two Color

Essay

In Lake Malawi cichlid fish, one can observe two color variants, Black Barred (BB) and Orange Blotch (OB). Sex in these fish is not determined by a sex chromosome but by a gene on an autosome, which produces either males or females. Both of these phenotypes are controlled by one biallelic locus each. OB females have a selective advantage in terms of their survivability: the OB phenotype allows females to blend into their background. OB males have a selective disadvantage because their reproductive coloration is disrupted and they have little mating success. How would this process influence the association of alleles at the color locus and sex-determining locus?