Sundaland

For other uses, see Sunderland (disambiguation).

"Sundas" redirects here. For the Greater Sundas, see Greater Sunda Islands. For the Lesser Sundas, see Lesser Sunda Islands.

The Sahul Shelf and the Sunda Shelf today. The area in between is called "Wallacea".

Sundaland is a biogeographical region of Southeastern Asia which encompasses the Sunda shelf; the part of the Asian continental shelf that was exposed during the last ice age. It included the Malay Peninsula on the Asian mainland, as well as the large islands of Borneo, Java, and Sumatra and their surrounding islands. The eastern boundary of Sundaland is the Wallace Line, identified by Alfred Russel Wallace, which marks the eastern boundary of the Asia's land mammal fauna, and is the boundary of the Indomalaya and Australasia ecozones. The islands east of the Wallace line are known as Wallacea, and are considered part of Australasia.

The new findings from Human Genome Organisation shows that Asian human population was populated primarily through a single migration event from the south, pointing the submerged Sundaland as the probable cradle of Asian human population.

History

The South China Sea and adjoining landmasses had been investigated by scientists such as Molengraaff and Umbgrove who had postulated ancient now submerged drainage systems. These have been mapped by Tjia in 1980 and described in greater detail by Emmel and Curray in 1982 complete with river deltas, floodplains and backswamps. The ecology of the exposed Sunda shelf has been investigated by analyzing cores drilled into the ocean bed. The pollens found in the cores have revealed a complex ecosystem that changed over time. The flooding of Sundaland separated species that had once shared the same environment such as the river threadfin (Polydactylus macrophthalmus, Bleeker 1858) that had once thrived in a river system now called "North Sunda River" or "Molengraaff river". Now the fish is known from the Kapuas River on Borneo and the Musi and Batanghari rivers on Sumatra in Indonesia.

Human migrations

Previously the human migrations was believed to take the direction Southward from East Asian mainland to Taiwan and to the rest of Maritime Southeast Asia. However recent findings pointing the submerged Sundaland as the probable cradle of Asian population, thus generated the "Out of Sundaland" theory.

A study from Leeds University and published in Molecular Biology and Evolution. Examination of mitochondrial DNA lineages shows that human have been evolving within Islands of Southeast Asia for a longer period than previously believed. Population dispersals occurred at the same time as sea levels rose, which may have resulted in migrations from the Philippine Islands to as far north as Taiwan within the last 10,000 years. The population migrations were most likely to have been driven by climate change — the effects of the drowning of a huge ancient continent Sundaland. This happened during the period 15,000 to 7,000 years ago following the last Ice Age. The rising sea levels in three massive pulses caused flooding and the submergence of the Sunda Continent, creating the Java and South China Seas and the thousands of islands that make up Indonesia and the Philippines today.

The new findings from Human Genome Organisation also shows that Asia was populated primarily through a single migration event from the south. They found genetic similarities between populations throughout Asia and an increase in genetic diversity from northern to southern latitudes. Although the Chinese population is very large, it has less variation than the smaller number of individuals living in Southeast Asia, because the Chinese expansion occurred very recently, following the development of rice agriculture — within only the last 10,000 years.

Oppenheimer locate the origin of the Austronesian in Sundaland and its upper regions. Genetic research reported in 2008 indicates that the islands which are the remnants of Sundaland were likely populated as early as 50,000 years ago, contrary to a previous hypothesis that they were populated as late as 10,000 years ago from Taiwan.

Ecology

The islands of Sundaland rest on an extension of Asia's shallow continental shelf called the Sunda shelf. During the ice ages, sea levels were lower and all of Sundaland was an extension of the Asian continent.

As a result, the islands of Sundaland are home to many Asian mammals including elephants, monkeys, apes, tigers, tapirs, and rhinoceros. The Wallace Line, which includes the Lombok Strait between Bali and Lombok, and the Makassar Strait between Borneo and Sulawesi, marks the end of the Asian continental shelf, and the islands of Wallacea are separated from Asia and from Australia and New Guinea by deep ocean.

Botanists often include Sundaland, the adjacent Philippines, Wallacea and New Guinea in a single Floristic province of Malesia, based on similarities in their flora, which is predominantly of Asian origin.

Ecoregions of Sundaland

Tropical and subtropical moist broadleaf forests

• Borneo lowland rain forests (Borneo)
• Borneo montane rain forests (Borneo)
• Borneo peat swamp forests (Borneo)
• Eastern Java–Bali montane rain forests (Bali, Java)
• Eastern Java–Bali rain forests (Bali, Java)
• Mentawai Islands rain forests (Mentawai Islands)
• Peninsular Malaysian montane rain forests (Malay peninsula)
• Peninsular Malaysian peat swamp forests (Malay peninsula)
• Peninsular Malaysian rain forests (Anambas Islands, Malay peninsula)
• Southwest Borneo freshwater swamp forests (Borneo)
• Sumatran freshwater swamp forests (Sumatra)
• Sumatran lowland rain forests (Sumatra, Nias, Bangka Island)
• Sumatran montane rain forests (Sumatra)
• Sumatran peat swamp forests (Sumatra)
• Sundaland heath forests (Indonesia)
• Western Java montane rain forests (Java)
• Western Java rain forests (Java)

Tropical and subtropical coniferous forests

• Sumatran tropical pine forests (Sumatra)

Montane grasslands and shrublands

• Kinabalu montane alpine meadows (Borneo)

Mangroves

• Sunda Shelf mangroves (Borneo, Sumatra, Riau Islands)

Notes and references

Further reading

• Stephen Oppenheimer. Eden in the East, 1999, Phoenix (Orion) ISBN 0-7538-0679-7

Selected faunal references in Borneo

• Abdullah MT. 2003. Biogeography and variation of Cynopterus brachyotis in Southeast Asia. PhD thesis. The University of Queensland, St Lucia, Australia.

• Corbet, GB, Hill JE. 1992. The mammals of the Indomalayan region: a systematic review. Oxford University Press, Oxford.

• Hall LS, Gordon G. Grigg, Craig Moritz, Besar Ketol, Isa Sait, Wahab Marni, Abdullah MT. 2004. Biogeography of fruit bats in Southeast Asia. Sarawak Museum Journal LX(81):191–284.

• Karim, C., A.A. Tuen, Abdullah MT. 2004. Mammals. Sarawak Museum Journal Special Issue No. 6. 80: 221—234.

• Mohd. Azlan J., Ibnu Maryanto, Agus P. Kartono, Abdullah MT. 2003 Diversity, Relative Abundance and Conservation of Chiropterans in Kayan Mentarang National Park, East Kalimantan, Indonesia. Sarawak Museum Journal 79: 251–265.

• Hall LS, Richards GC, Abdullah MT. 2002. The bats of Niah National Park, Sarawak. Sarawak Museum Journal. 78: 255–282.

• Wilson DE, Reeder DM. 2005. Mammal species of the world. Smithsonian Institution Press, Washington DC.

See also

• Sunda Islands
  • Greater Sunda Islands
  • Lesser Sunda Islands
• Sunda Trench
• Australasia
• Oceania
• Biogeography
• Plate tectonic

External links

• Conservation International: Sundaland
• Review of Oppenheimer's Eden in the East, about Sundaland
• Animation of Sundaland submersion