Question

Certain butterfly species have two morphs in the population. Most individuals have dark wings, but a few individuals in a population have light wings. a. A dark-winged female is crossed to a dark-winged male. In the F1, the male progeny all have dark wings, but half the females have dark wings and the rest have light wings. Using clearly defined symbols propose a genetic explanation for this pattern of inheritance. b. From the F1 generation, a dark-winged male is crossed to a light-winged female. What is the outcome in the F2 progeny? Show all possible outcomes.

Answer 1

Female - XDXD male-XDYd D= dark winged d= light winged

F1 progeny in normal case:

XDXD(dark winged female) : XDYd(dark winged male): XDXD( dark winged female): XDYd(dark winged male)

But as per the question, half of the females had light wings

This maybe due to the phenomenon of epistasis where the presence of one gene may mask the effect of other gene completely. Epistasis may have caused a mutational change in the X chromosomal inheritance of the wing color

b. If a dark winged male is crossed with a light winged female:

XDYD x XDXd

Possible outcomes :

XDXD XDXd XDYD XdYD