Geckos are a type of small lizard that live in tropical areas. Geckos are often eaten by birds, snakes and larger lizards so they need to blend into their surroundings. In one area, scientists had always found brown and green geckos that blended in with the grass and the leaves on the ground. Over time, though they found yellow geckos in the same population. Three students were talking about why there were yellow geckos. Ciena thought that the change came from a mutation in the population. Tibor thought the change came from the environment. Sasha though that Ciena and Tibor were both right. Who do you agree with and why do you think that?