Island Southeast Asia

Biogeography

Island Southeast Asia is crossed by the Wallace Line. This line divides the flora and fauna of Asia from that of Australia and New Guinea with stretches of water that have always been too wide for plant and animal species to cross readily. The gaps are considered to be large enough to make accidental rafting from one side to another to be unlikely events. Apart from birds, species that have managed to cross this line include those that have been moved by humans. There is a transitional zone adjacent to the Wallace Line that is termed Wallacea. This is a zone where examples of animal and plant species from both sides can be found, but, particularly on smaller islands, there may be a greatly reduced number of terrestrial species.