Wallace's Line
Alfred Wallace, a famous biogeographer, was traveling around the Malay archipelago, when he noticed the sudden difference in bird species when he sailed from Bali to Lombok, which was only twenty miles away. On Bali, the birds were similar to the birds on the larger islands of Java and Sumatra and mainland Malaysia. The birds on Lombok were very different. On Bali, he never saw the white cockatoo which he found on LombokBali was once connected to Java and Sumatra. So its species were related. Although Lombok was geographically close, it was in much deeper water and totally isolated. Wallace noticed that Lombok's birds and animals were more similar to those on Australia and New Guinea. Wallace said the channel between Bali and Lombok was the divide between two zoogeographic regions, the Oriental and Australian. This means that the species between these two regions, even places that were very close, were very different. This dividing line is called Wallace's Line.