A large population of butterflies lives in southeastern Asia. About half have spots and half don’t. In 1995, a rare viral illness was introduced to the population, and there was no cure. More spotted butterflies than un-spotted butterflies were killed by the illness, although the fact that they had spots had no bearing on their risk for illness. Which evolutionary mechanism is this an example of? A)Genetic drift
B)Geographic isolation
C)DNA mutations
D)Reproductive isolation