You encounter someone who has never heard of evolution, and they ask you about a population of ducks that live in their grandmothers pond. They tell you that 10 years ago the pong had both large eyed ducks and small eyed ducks. But one day 2 of the large eyed ducks were killed by some wild dogs. Now, the population of ducks has entirely small eyed. Identify the mechanism of change in the duck scenario and use it as evidence to explain evaluation to that person.

The large eyed ducks had an undesirable trait, but the small eyed ducks have a desirable trait. Because the large eyed ducks had a trait that decreases their chances of survival, they wete killed. But small eyed ducks are lucky because they have a trait that increases their chance of survival. The small eyed ducks reproduce more offspring that have small eyes, but the large eyed ducks cannot because they didn't survive. This causes that the allele for large eyes in the gene pool to decrease.