Question

From a population of red brown orange yellow and green butterflies only the red and green ones survive since they can blend into their environment and reduce predation. Which evolutionary mechanism is involved?

Answer 1

The trait of the Red and green the trait to be able to blend into the background. 

Answer 2

The answer is natural selection. Since the brown, yellow, and orange butterflies aren't able to blend into their environment their genes wont be passed down to the next generation.