Borneo Elephant
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A new study settles a long-standing dispute about the genesis of an endangered species. With scant fossil evidence supporting a prehistoric presence, scientists could not say for sure where Borneo's elephants came from. Did they descend from ancient prototypes of the Pleistocene or from modern relatives introduced just 300–500 years ago?.
Applying DNA analysis and dating techniques to investigate the elephants's evolutionary path, researchers from the United States, India, and Malaysia, led by Don Melnick of the Center for Environmental Research and Conservation at Columbia, demonstrate that Borneo's elephants are not recent arrivals. They are genetically distinct from other Asian elephants and may have parted ways with their closest Asian cousins when Borneo separated from the mainland, effectively isolating the Borneo elephants some 300,000 years ago.
Borneo Elephant
In the 1950s, Borneo elephants had been classified as a subspecies of Asian elephants (either Indian or Sumatran) based on anatomical differences, such as smaller skull size and tusk variations. This classification was later changed, partly because of the popular view that these animals had descended from imported domesticated elephants. Until now, there was no solid evidence to refute this belief and no reason to prioritize the conservation of Borneo elephants.
Their new status, as revealed by this study, has profound implications for the fate of Borneo's largest mammals. Wild Asian elephant populations are disappearing as expanding human development disrupts their migration routes, depletes their food sources, and destroys their habitat. Recognizing these elephants as native to Borneo makes their conservation a high priority and gives biologists important clues about how to manage them.
Elephants have a very limited distribution in Borneo, being restricted to approximately 5% of the island in the extreme northeast There are no historical records of elephants outside of this range. Fossil evidence for the prehistoric presence of elephants on Borneo is limited to a single specimen of a tooth from a cave in Brunei (Hooijer 1972).
Popular belief holds that elephants presented to the Sultan of Sulu in 1750 by the East India Trading Company and subsequently transported to Borneo founded the current population (Harrisson and Harrisson 1971; Medway 1977). These animals presumably originated in India (Shoshani and Eisenberg 1982), where company operations and trade in domesticated elephants were centred. Alternatively, considering the geographic proximity to Borneo, the elephant trade that flourished in Sumatra and peninsular Malaysia during the 16th–18th centuries (Andaya 1979; Marsden 1986[1811]) may have been the source. Thus, if elephants were introduced to Borneo, the source population could have been India, Sumatra, or peninsular Malaysia, and as a feral population, Borneo's elephants would have low conservation importance.
Conversely, if elephants occurred naturally on Borneo, they would have colonised the island during Pleistocene glaciations, when much of the Sunda shelf was exposed and the western Indo-Malayan archipelago formed a single landmass designated as Sundaland (MacKinnon et al. 1996). Thus, the isolation of Borneo's elephants from other conspecific populations would minimally date from the last glacial maximum, 18,000 years ago, when land bridges last linked the Sunda Islands and the mainland (MacKinnon et al. 1996). If Borneo's elephants are of indigenous origin, this would push the natural range of Asian elephants 1300 km to the east, and as a unique population at an extreme of the species' range, Borneo elephants' in situ conservation would be a priority and ex situ cross-breeding with other populations would be contraindicated.
Initially, Borneo elephants were classified as a unique subspecies (Elephas maximus borneensis) based on morphological differences from other populations (Deraniyagala 1950, 1955). Subsequently, they were subsumed under the Indian Elephas maximus indicus (Shoshani and Eisenberg 1982) or the Sumatran Elephas maximus sumatrensis (Medway 1977) subspecies, based on an assumption of their introduction to the region or on the reasoning that morphological divergence was insufficient to warrant separate status. While unique subspecific status would highlight their conservation importance, evaluation of their status in terms of evolutionary significant units (ESUs) and management units (MUs) (Ryder 1986; Moritz 1994) would be more relevant to conservation management.
The original article at [1] contains details on the DNA research including many references which are relevant to that aspect of the article. References cited in this article include:
- Barbara Watson Andaya, Perak, the abode of grace: A study of an eighteenth-century Malay state, Oxford University Press, 1990, hardcover, 462 pages, ISBN 019580385X
- Deraniyagala PEP (1950) The elephant of Asia. Proc Ceylon Assoc Sci 3: 1–18.
- Deraniyagala PEP (1955) Some extinct elephants, their relatives, and the two living species. Colombo, Ceylon: Government Press. 161pages
- Tom and Barbara Harrisson, The prehistory of Sabah Sabah Society Journal, Volume IV, 1969-1970 (1971), monograph pages 1-272
- Hooijer DA (1972) Prehistoric evidence for Elephas maximus L. in Borneo. Nature 239: 228.
- Lord Medway, Mammals of Borneo - Field Keys and an Annotated Checklist, monograph, Malaysian Branch of the Royal Asian Society volume 7, 1965, 193 pages
- William Marsden, introduction by John Bastin, The History of Sumatra (Oxford in Asia Hardback Reprints) Oxford University Press, reprinted in 1986, orginally published in 1793 or 1811, hardcover, 532 pages, ISBN 0195826701
- Kathy MacKinnon, Gusta Hatta, Hakimah Halim and Arthur Mangalik, The Ecology of Kalimantan (Indonesian Borneo), Periplus Editions Ltd., Hong Kong, 1997, hardcover, 802 pages, ISBN 0945971737
- Shoshani J, Eisenberg JF (1982) Elephas maximus. Mammalian Species 182: 1–8.
Based on the article, DNA Analysis Indicates That Asian Elephants Are Native to Borneo and Are Therefore a High Priority for Conservation [2]. Authors; Prithiviraj Fernando–Center for Environmental Research and Conservation, Columbia University, New York, New York, United States of America, Department of Ecology, Evolution, and Environmental Biology, Columbia University, New York, New York, United States of America , T. N. C. Vidya–Center for Ecological Sciences, Indian Institute of Science, Bangalore, India , John Payne–World Wide Fund for Nature–Malaysia, Kota Kinabalu, Sabah, Malaysia, Michael Stuewe–Asian Rhino and Elephant Action Strategy Programme, World Wildlife Fund, Washington, District of Columbia, United States of America, Geoffrey Davison–World Wide Fund for Nature–Malaysia, Kota Kinabalu, Sabah, Malaysia, Raymond J. Alfred–World Wide Fund for Nature–Malaysia, Kota Kinabalu, Sabah, Malaysia, Patrick Andau–Sabah Wildlife Department, Kota Kinabalu, Sabah, Malaysia, Edwin Bosi–Sabah Wildlife Department, Kota Kinabalu, Sabah, Malaysia, Annelisa Kilbourn, deceased, –Field Veterinary Program, Wildlife Conservation Society, Bronx, New York, United States of America� (In the online version of this article published on August 18, Annelisa Kilbourn's affiliation was incorrectly identified as the Sabah Wildlife Department. Her proper affiliation is shown here.), Don J. Melnick–Center for Environmental Research and Conservation, Columbia University, New York, New York, United States of America, Department of Ecology, Evolution, and Environmental Biology, Columbia University, New York, New York, United States of America. Academic Editor: Craig Moritz, University of California, Berkeley.
Abbreviations: ESU, evolutionary significant unit; mtDNA, mitochondrial DNA; MU, management unit.
Correspondence regarding the original article should be addressed to E-mail: pf133@columbia.edu. Published August 18, 2003, in the online journal PLoS Biology.
Copyright: � 2004 Fernando et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
