A population of butterfly has individuals with normal wings (no black spots) and individuals with black spots on their wings. You were walking in the forest and accidentally stepped on these butterflies and killed a significant number of individuals in the population. As a result, the allelic frequency of "normal wings" and "wings with a black spot" will likely to change in this population in the next generation due to the loss of these individuals.
Which mechanism of evolution is portrayed in this example?
O Mutation
O Genetic drift
O Migration (gene flow)
O Natural Selection