Human activity has changed biodiversity on islands by altering habitats and introducing new species. By updating island biogeography theory, scientists predict that as land development and global trade increase, the number of species on islands will change. More diverse habitats lead to more species, while being closer to other sources of species also increases diversity. Economic factors also play a role, with larger economies having more species. This updated theory helps us understand how biodiversity on islands is changing in the modern world.