The scientists studied different regions in Brazil to understand why animal species vary from place to place. They used two methods to figure out if the differences were due to new species coming in or species disappearing. They found that one method showed more turnover of species than the other, but both methods showed similar patterns. The differences in species were influenced by how well animals can move around and the environment they live in. This shows that the variety of animal species in an area is influenced by both the environment and how far animals can travel.