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
Blakiston's Line Blakiston's Line, there are very many that can be found at either side of the line, in part because of human involvement. Examples of the latter are the Japanese Shorthorn, a breed of small Japanese beef cattle that is distributed in northern Honshu and also in Hokkaido, and the Japanese weasel, which was introduced to Hokkaido by human intervention. It has also been studied whether or not this biogeographic boundary applies to far smaller organisms like soil microbes. Apart from Blakiston's Line, other faunal boundary lines have been proposed for Japan, like Watase’s line (Tokara Straits): for mammals, reptiles, amphibians