Download Lecture Slides on The Wallace Line - Plant Geography | BOTANY 422 and more Study notes Geography in PDF only on Docsity! 1 The Wallace Line Alfred Wallace, one of the premier zoobiogeographers, wrote the definitive treatise “Distributions of Animals” in 1876 where he summarized the known distributions and causes of their biogeographical patterns Alfred Wallace’s main interest was in the vertebrate fauna of the Indo-Malay Archipelago from Asia to Australia where he clearly saw a sharp faunistic break Wallace’s trips Sclater’s & Wallace’s faunistic regions Probably his most important trip he ever made was a 6 km ferry ride from Bali to Lombok The Wallace Line “In the archipelago . . . there are two distinct faunas rigidly circumscribed, which differ as much as those of South America and Africa, and more than those of Europe and North America” [Letter to Henry Bates in London (1858)] Sclater’s & Wallace’s faunistic regions Wallace’s trips The Wallace Line “The boundary line often passes between islands closer than others in the same group. I believe the western part to be a separated portion of continental Asia, the eastern the fragmentary prolongation of a former Pacific continent” Looking east from Bali across 6 km Lombok Straits “In the archipelago . . . there are two distinct faunas rigidly circumscribed, which differ as much as those of South America and Africa, and more than those of Europe and North America” [Letter to Henry Bates in London (1858)] The Wallace Line 2 Cover plate from Distributions of Animals Wallace graphically depicts what has since been termed the “Wallace Line” in his book by showing birds and mammals that are found in the Oriental (Borneo, left) and Australian (New Guinea, right) sides tarsier tree kangaroo tree shrew tapir lory raquet-tailed kingfisher Oriental Fauna Australian Fauna The Wallace Line • Wallace Line — the imaginary line separating the Oriental and Australian biotas — extends between Bali and Lombok and between Borneo/Philippines and Sulawesi • Several other lines have been proposed in the region based on particular groups of animals or plants. • Main issue with most lines is what do with Sulawesi (Celebes) The Wallace Line Crested black macaque Bear cuscus (marsupial) Backbone of Sulawesi Sulawesi, with its mixture of Oriental and Australian fauna, was so perplexing to Wallace, that he vacillated back and forth on where to place the island The Wallace Line Now know that the two regions are different continental plates that have been moving independently — the Asian and Australian plates The IndoMalay - New Guinea Archipelago area includes island groups mostly confined to either of two continental shelves: Sunda shelf — Asian Sahul shelf — Australian The Wallace Line
