Wharthogs on Planet Zeta are either white or purple A purebr

Wharthogs on Planet Zeta are either white or purple. A pure-bred male white Wharthog was mated with a pure-bred female purple Wharthog. They had ninety progeny, all of whom were purple. [Wharthogs are very prolific, especially in the special atmosphere on Planet Zeta.] P white X purple F1 all purple (ninety total) F2 900 purple 700 white The ninety F1 progeny were randomly interbred and produced a total of 1600 F2 progeny. Nine hundred of these F2 progeny were purple and 700 were white. A. Based on this data alone, how many genetic loci control skin color in Wharthogs? Explain in detail.

Solution

Pure breeding white and purple gives all purple progeny in F1 generation which means that purple is dominant over white. The dihybrid cross between F1 purple gives purple and white in 9:7 ratio which is a modification of 9:3:3:1. If the two genetic loci C and P are responsible for coat color; presence of atleast one copy of dominant C and P gives purple coat color while \"P\" and \"C\" alone can not produce the purple coat color and give \"white coat color only.
Pure breeding purple (CCPP) and white (ccpp) produced all purple progeny (CcPp). The cross between two F1 (CcPp x CcPp) gives 9 purple (C-P-) and 7 white (cc-P-, C-pp and ccpp) phenotypes. Hence it is the epistatic inheritance and \"two genetic loci\" are involved in the inheritance.