The scientists examined how different types of small animals in the Andes Mountains change as you go up the mountain. They wanted to see if the animals at different elevations were mainly switching out or if some animals were completely missing. They discovered that at higher elevations, there were more types of animals but fewer individual animals. As they climbed higher, they found that most animals were changing rather than the overall number of animals. They also noticed that the variety of animals was jumping around at the different elevations rather than following a smooth pattern. This information helps us understand how animals are spread out in these mountain areas and can help identify which areas and animals might need protection.