Written-Response Question #1 Guppies are small fish that live in South American rivers. They can have different-sized spots on their bodies. The river bottoms are covered in rocks. Guppies with spots that are the same size as the rocks on the bottom are harder for bigger fish to see and catch. The diagram above shows a population of guppies that lived in a river. Scientists had previously only seen guppies with medium or large spots in this river; they had never seen any guppies with any other spot sizes. The diagram below shows how the population changed after many generations.

• Karina says the change in the guppy population was caused by a mutation.

• Miles says the change was caused by a change in the environment.

• Zora thinks both Karina and Miles are correct.

Who do you think is right? Explain what happened to the guppies over many generations