Eye color of the Oriental fruit fly Bactrocera dorsalis is d

Eye color of the Oriental fruit fly (Bactrocera dorsalis) is determined by a number of genes. A fly having wild-type eyes is crossed with a fly having yellow eyes. All the F_1 flies from this cross have wild type eyes. When the F_1 are interbred, 9/16 of the F_2 progeny have wild-type eyes, 3/16 have amethyst eyes (a bright, sparkling blue color), and 4/16 have yellow eyes. (a) Give genotypes for all the flies in the P, F_1, and F_2 generations. (b) Does epistasis account for eye color in Oriental fruit flies? If so, which gene is epistatic and which gene is hypostatic?

Solution

A) Genotypes:-   WE(wild type eyes) x ye(Yellow eyes) -----> WEye(wild type eyes) --F1 progeny

F2 progeny:-- Punnett square

|     WE | We | yE | ye

WE | WWEE | WWEe | WyEE | WyEe   

We | WWEe | WWee | WyEe | Wyee

yE | WyEE | WyEe | yyEE | yyEe

ye | WyEe I Wyee | yyEe | yyEe      

Phenotypic ratio -- 9 : 3 :4

Wid eyes: Amethyst eyes : yellow eyes.   

B) Yes, epistasis account for eye colour.Its recessive epistasis because some of the eye colour aren\'t similar to their parent.F1 progeny are epistatic and F2 progenies are hypostatic.