Wallace Line to the west of the Philippines. Wallace's studies in Indonesia demonstrated the emerging theory of evolution, at about the same time as Joseph Dalton Hooker and Asa Gray published essays also supporting Darwin's hypothesis. Understanding of the biogeography of the region centers on the relationship of ancient sea levels to the continental shelves. Wallace's Line is visible geographically when the continental shelf contours are examined; it can be seen as a deep-water channel that marks the southeastern edge of the Sunda Shelf which links Borneo, Bali, Java, and Sumatra underwater to the mainland of southeastern Asia. Australia is likewise connected
Alfred Russel Wallace the Cambridge University Museum of Zoology. His observations of the marked zoological differences across a narrow strait in the archipelago led to his proposing the zoogeographical boundary now known as the Wallace line. Wallace collected more than 126,000 specimens in the Malay Archipelago (more than 80,000 beetles alone). Several thousand of them represented species new to science. One of his better-known species descriptions during this trip is that of the gliding tree frog "Rhacophorus nigropalmatus", known as Wallace's flying frog. While he was exploring the archipelago, he refined his thoughts about evolution and had his famous insight on natural selection.