Why this 'imaginary' line separates Asian animals from the species you find in Australia

A fascinating biological phenomenon occurs between two islands in Indonesia. An invisible line divides the entire Malay Archipelago, and on the western side, the animal life is characteristic of Asia, featuring rhinos, elephants, tigers and woodpeckers. Contrasting this, the eastern side of the islands presents a completely different ecological cast, boasting marsupials, Komodo dragons, cockatoos …