The Bornean elephant is genetically different than its mainland relatives, the Asian elephant. Photo by Rudi Delvaux
Jan. 17 (UPI) -- Genetic analysis has offered new insights into how the Bornean elephant, a subspecies of the Asian elephant, came to occupy a small portion of the island of Borneo in Southeast Asia.
Until now, the origins of the Bornean elephant were a mystery. But the latest analysis, published this week in the journal Scientific Reports, suggests the elephants crossed the last land bridge linking the mainland and the Sundra Islands.
The Bornean pigmy elephant grows to a height of eight feet, two feet shorter than Asian elephants. They're known for their baby-like face and giant ears. They live in the Malaysian state of Sabah.
Previously, scientists had considered the possibility that Bornean elephants were brought to the island by humans some 300 years ago. Historical documents suggest neighboring sultans had offered elephants as a gift.
Previous DNA analysis, however, showed the Bornean elephant was genetically unique. The data suggested the subspecies arrived on the island some 300,000 years ago. But scientists have yet to find ancient elephant fossils.
As part of the new study, scientists decided to reexamine the genetic data using advanced modeling techniques.
"What we did was to create computational models for different scenarios that might have happened," Lounès Chikhi, a researcher with the Instituto Gulbenkian de Ciência in Portugal, said in a news release. "Then, we compared the results from these models with the existing genetic data, and used statistical techniques to identify the scenario that best explained the current genetic diversity of the elephant population in Borneo."
The models suggest the Bornean elephant arrived between 18,300 and 11,400 to 18,300 years ago, which explains why scientists have yet to find elephant bones among more ancient strata.
"This period corresponds to a time when the sea levels were very low and elephants could migrate between the Sunda Islands, a Southeastern Asia archipelago to which Borneo belongs," said IGC researcher Reeta Sharma. "We cannot exclude more complex scenarios, but a historical human introduction seems very improbable, and so does a very ancient arrival."
Researchers hope their improved understanding of the Bornean elephant's origins will help craft more effective conservation plans for the severely endangered subspecies. The elephants face threats of deforestation, habitat fragmentation and predation by humans. The elephants are regularly poisoned by local palm oil farmers who see the mammals as pests.