Parts of this article (those related to Christmas Island) need to be updated. Please help update this article to reflect recent events or newly available information.(March 2020)
The Wallace Line or Wallace's Line is a faunal boundary line drawn in 1859 by the British naturalist Alfred Russel Wallace and named by English biologist Thomas Henry Huxley that separates the biogeographic realms of Asia and Wallacea, a transitional zone between Asia and Australia. West of the line are found organisms related to Asiatic species; to the east, a mixture of species of Asian and Australian origin is present. Wallace noticed this clear division during his travels through the East Indies in the 19th century.
Wallace's Line delineates Australian and Southeast Asian fauna. The probable extent of land at the time of the Last Glacial Maximum, when the sea level was more than 110 m (360 ft) lower than today, is shown in grey. The deep water of the Lombok Strait between Bali and Lombok formed a water barrier even when lower sea levels linked the now-separated islands and landmasses on either side.
The line runs through Indonesia, between Borneo and Sulawesi (Celebes), and through the Lombok Strait between Bali and Lombok. The distance between Bali and Lombok is small, about 35 kilometres (22 mi). The distributions of many bird species observe the line, since many birds do not cross even the shortest stretches of open ocean water. Some bats have distributions that cross the line, but larger terrestrial mammals are generally limited to one side or the other; exceptions include macaques, pigs and tarsiers on Sulawesi. Other groups of plants and animals show differing patterns, but the overall pattern is striking and reasonably consistent. Flora do not follow the Wallace Line to the same extent as fauna.[1] One genus of plants that does not cross the Line is the Australasian genus Eucalyptus, except for one species, Eucalyptus deglupta, which naturally occurs on the island of Mindanao in the Philippines.
The original drawing of the line from Wallace's paper
The Venetian explorer Antonio Pigafetta had recorded the biological contrasts between the Philippines and the Maluku Islands (Spice Islands) (on opposite sides of the line) in 1521 during the continuation of the voyage of Ferdinand Magellan, after Magellan had been killed on Mactan. Moreover, as noted by Wallace himself, the observations in faunal differences between the two regions had already been made earlier by English navigator George Windsor Earl published in 1845. In Wallace's 1863 paper On the Physical Geography of South-Eastern Asia and Australia, he described how shallow seas connected islands on the west (Sumatra, Java, etc.) with the Asian continent and with similar wildlife, and islands on the east such as New Guinea were connected to Australia and were characterised by the presence of marsupials. Wallace used his extensive travel in the region to propose a line to the east of Bali since "all the islands eastward of Borneo and Java formed part of an Australian or Pacific Continent, from which they were separated."[2] The name 'Wallace's Line' was first used by Thomas Huxley in an 1868 paper to the Zoological Society of London, but showed the line to the west of the Philippines.[3][4] 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.[5]
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 by the Sahul Shelf to New Guinea. The biogeographic boundary known as Lydekker's Line, which separates the eastern edge of Wallacea from the Australian region, has a similar origin to the Wallace Line.
During ice ageglacial advances, when the ocean levels were up to 120 metres (390 ft) lower, both Asia and Australia were united with what are now islands on their respective continental shelves as continuous land masses, but the deep water between those two large continental shelf areas was, for over 50 million years, a barrier that kept the flora and fauna of Australia separated from those of Asia. Wallacea consists of islands that were not recently connected by dry land to either of the continental land masses, and thus were populated by organisms capable of crossing the straits between islands. "Weber's Line" runs through this transitional area (to the east of centre), at the tipping point between dominance by species of Asian against those of Australian origin.[6]
It can reasonably be concluded it was an ocean barrier preventing species migration because the physical aspects of the separated islands are very similar.[7] Species found only on the Asian side include tigers and rhinoceroses, while marsupials and monotremes are only found on the eastern side of the Line.[8]
^Van Welzen, P. C.; Parnell, J. A. N.; Slik, J. W. F. (2011). "Wallace's Line and plant distributions: Two or three phytogeographical areas and where to group Java?". Biological Journal of the Linnean Society. 103 (3): 531–545. doi:10.1111/j.1095-8312.2011.01647.x.
^Huxley, T. H. (1868). "On the Classification and Distribution of the Alectoromorphae and Heteromorphae". Proceedings of the Zoological Society of London: 294–319. Retrieved Apr 25, 2015.
^Camerini, Jane R. (1993). "Evolution, Biogeography, and Maps". Isis. 84 (4): 700–727. doi:10.1086/356637. PMID 8307726. S2CID 15219070.
^Bowler, Peter J. (1989). Evolution: The History of an Idea. University of California Press. p. 193. ISBN0520063864. Retrieved 15 February 2016.
^Newton, Alfred (1874). Zoology. Society for Promoting Christian Knowledge. p. 51. Retrieved 15 February 2016.
^Riley, Laura; William Riley (2005). Nature's Strongholds: The World's Great Wildlife Reserves. Princeton University Press. p. 602. ISBN0691122199. Retrieved 15 February 2016.
References
Wallace, Alfred Russel (1863). "On the Physical Geography of the Malay Archipelago". Royal Geographical Society. 7: 205–212. with the original paper
Further reading
van Oosterzee, Penny (1997). Where Worlds Collide: the Wallace Line.
Abdullah, M. T. (2003). Biogeography and variation of Cynopterus brachyotis in Southeast Asia. PhD thesis. The University of Queensland, St Lucia, Australia.
Hall, L. S., Gordon G. Grigg, Craig Moritz, Besar Ketol, Isa Sait, Wahab Marni and M. T. Abdullah (2004). "Biogeography of fruit bats in Southeast Asia". Sarawak Museum Journal LX(81):191-284.
Wilson D. E., D. M. Reeder (2005). Mammal species of the world. Washington DC: Smithsonian Institution Press.
External links
Wikimedia Commons has media related to Wallace Line.
Too Many Lines; The Limits of the Oriental and Australian Zoogeographic Regions George Gaylord Simpson, Proceedings of the American Philosophical Society, Vol. 121, No. 2 (Apr. 29, 1977), pp. 107–120
Wallacea Research Group
Map of Wallace's, Weber's and Lydekker's lines
Pleistocene Sea Level Maps
Wallacea - a transition zone from Asia to Australia, specially rich in marine life and on land
January 08, 2023
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Parts of this article those related to Christmas Island need to be updated Please help update this article to reflect recent events or newly available information March 2020 The Wallace Line or Wallace s Line is a faunal boundary line drawn in 1859 by the British naturalist Alfred Russel Wallace and named by English biologist Thomas Henry Huxley that separates the biogeographic realms of Asia and Wallacea a transitional zone between Asia and Australia West of the line are found organisms related to Asiatic species to the east a mixture of species of Asian and Australian origin is present Wallace noticed this clear division during his travels through the East Indies in the 19th century Wallace s Line delineates Australian and Southeast Asian fauna The probable extent of land at the time of the Last Glacial Maximum when the sea level was more than 110 m 360 ft lower than today is shown in grey The deep water of the Lombok Strait between Bali and Lombok formed a water barrier even when lower sea levels linked the now separated islands and landmasses on either side The line runs through Indonesia between Borneo and Sulawesi Celebes and through the Lombok Strait between Bali and Lombok The distance between Bali and Lombok is small about 35 kilometres 22 mi The distributions of many bird species observe the line since many birds do not cross even the shortest stretches of open ocean water Some bats have distributions that cross the line but larger terrestrial mammals are generally limited to one side or the other exceptions include macaques pigs and tarsiers on Sulawesi Other groups of plants and animals show differing patterns but the overall pattern is striking and reasonably consistent Flora do not follow the Wallace Line to the same extent as fauna 1 One genus of plants that does not cross the Line is the Australasian genus Eucalyptus except for one species Eucalyptus deglupta which naturally occurs on the island of Mindanao in the Philippines Contents 1 Historical context 2 Biogeography 3 See also 4 Citation and notes 5 References 6 Further reading 7 External linksHistorical context Edit The original drawing of the line from Wallace s paper The Venetian explorer Antonio Pigafetta had recorded the biological contrasts between the Philippines and the Maluku Islands Spice Islands on opposite sides of the line in 1521 during the continuation of the voyage of Ferdinand Magellan after Magellan had been killed on Mactan Moreover as noted by Wallace himself the observations in faunal differences between the two regions had already been made earlier by English navigator George Windsor Earl published in 1845 In Wallace s 1863 paper On the Physical Geography of South Eastern Asia and Australia he described how shallow seas connected islands on the west Sumatra Java etc with the Asian continent and with similar wildlife and islands on the east such as New Guinea were connected to Australia and were characterised by the presence of marsupials Wallace used his extensive travel in the region to propose a line to the east of Bali since all the islands eastward of Borneo and Java formed part of an Australian or Pacific Continent from which they were separated 2 The name Wallace s Line was first used by Thomas Huxley in an 1868 paper to the Zoological Society of London but showed the line to the west of the Philippines 3 4 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 5 Biogeography Edit The Wallacea region situated between the Wallace Line after Ernst Mayr or Thomas Henry Huxley and the Lydekker Line 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 by the Sahul Shelf to New Guinea The biogeographic boundary known as Lydekker s Line which separates the eastern edge of Wallacea from the Australian region has a similar origin to the Wallace Line During ice age glacial advances when the ocean levels were up to 120 metres 390 ft lower both Asia and Australia were united with what are now islands on their respective continental shelves as continuous land masses but the deep water between those two large continental shelf areas was for over 50 million years a barrier that kept the flora and fauna of Australia separated from those of Asia Wallacea consists of islands that were not recently connected by dry land to either of the continental land masses and thus were populated by organisms capable of crossing the straits between islands Weber s Line runs through this transitional area to the east of centre at the tipping point between dominance by species of Asian against those of Australian origin 6 It can reasonably be concluded it was an ocean barrier preventing species migration because the physical aspects of the separated islands are very similar 7 Species found only on the Asian side include tigers and rhinoceroses while marsupials and monotremes are only found on the eastern side of the Line 8 See also Edit Indonesia portal Evolutionary biology portal Geography portalAustralasian realm One of the Earth s eight biogeographic realms Australia continent One of Earth s seven main divisions of land Wallacea Biogeographical regionCitation and notes Edit Van Welzen P C Parnell J A N Slik J W F 2011 Wallace s Line and plant distributions Two or three phytogeographical areas and where to group Java Biological Journal of the Linnean Society 103 3 531 545 doi 10 1111 j 1095 8312 2011 01647 x Wallace 1863 pp 205 212 Huxley T H 1868 On the Classification and Distribution of the Alectoromorphae and Heteromorphae Proceedings of the Zoological Society of London 294 319 Retrieved Apr 25 2015 Camerini Jane R 1993 Evolution Biogeography and Maps Isis 84 4 700 727 doi 10 1086 356637 PMID 8307726 S2CID 15219070 Bowler Peter J 1989 Evolution The History of an Idea University of California Press p 193 ISBN 0520063864 Retrieved 15 February 2016 Mayr E 1944 Wallace s Line in the Light of Recent Zoogeographic Studies The Quarterly Review of Biology 19 1 1 14 doi 10 1086 394684 JSTOR 2808563 S2CID 33245177 Newton Alfred 1874 Zoology Society for Promoting Christian Knowledge p 51 Retrieved 15 February 2016 Riley Laura William Riley 2005 Nature s Strongholds The World s Great Wildlife Reserves Princeton University Press p 602 ISBN 0691122199 Retrieved 15 February 2016 References EditWallace Alfred Russel 1863 On the Physical Geography of the Malay Archipelago Royal Geographical Society 7 205 212 with the original paperFurther reading Editvan Oosterzee Penny 1997 Where Worlds Collide the Wallace Line Dawkins Richard 2004 The Ancestor s Tale Weidenfeld amp Nicolson ISBN 0 7538 1996 1 Chapter 14 Marsupials Abdullah M T 2003 Biogeography and variation of Cynopterus brachyotis in Southeast Asia PhD thesis The University of Queensland St Lucia Australia Hall L S Gordon G Grigg Craig Moritz Besar Ketol Isa Sait Wahab Marni and M T Abdullah 2004 Biogeography of fruit bats in Southeast Asia Sarawak Museum Journal LX 81 191 284 Wilson D E D M Reeder 2005 Mammal species of the world Washington DC Smithsonian Institution Press External links Edit Wikimedia Commons has media related to Wallace Line Too Many Lines The Limits of the Oriental and Australian Zoogeographic Regions George Gaylord Simpson Proceedings of the American Philosophical Society Vol 121 No 2 Apr 29 1977 pp 107 120 Wallacea Research Group Map of Wallace s Weber s and Lydekker s lines Pleistocene Sea Level Maps Wallacea a transition zone from Asia to Australia specially rich in marine life and on land Retrieved from https en wikipedia org w index php title Wallace Line amp oldid 1132264461, wikipedia, wiki, book, books, library,
