In a species of tropical fish, a colorful orange and black variety called Montezuma occurs. When two Montezumas are crossed, 2/3 of the progeny are Montezuma, and 1/3 are wild-type, having a dark grayish green color. Montezuma is a single-gene trait, and the Montezuma fish are never true-breeding.
a. Explain the inheritance pattern seen here and how your explanation accounts for the phenotypic ratios given. Define symbols for each allele, show the parental genotypes and show a Punnett square as part of your answer.
b. In this same species, the morphology of a dorsal fin can be normal (designated D) or ruffled by homozygosity for a recessive allele designated d. What would be the genotypes and phenotypes of the progeny and in what proportions, from a cross of a Montezuma fish that is homozygous for normal fins to a green, ruffled fish. Show a Punnett square part of your answer.
c. What would be the phenotype of the offspring and the proportions from the crossing of two of the Montezuma progeny from part b? Show the genotypes of the parents, a Punnett square, the genotypic classes, the proportions and the corresponding phenotypes.