How did Borneo get its elephant? This could be just another of Rudyard Kipling’s just so stories. The Bornean elephant is a subspecies of Asian Elephants that only exist in a small region of Borneo. Their presence on this southeastern Asian island has been a mystery. Now, in a study published in Scientific Reports, a research team led by Lounès Chikhi from Instituto Gulbenkian de Ciência (IGC, Portugal) and CNRS, Université Paul Sabatier (France), and Benoit Goossens, from Cardiff University (Wales), and Sabah Wildlife Department (Malaysia), found that elephants might have arrived on Borneo at a time of the last land bridge between the Sunda Islands in Southeast Asia.
Until recently, two opposing theories have been under debate to explain the origin of Bornean elephants: they could have been recently introduced by humans, maybe 300 years ago, or they could have diverged from Asian elephants a long time ago. Indeed, there are historic records reporting that, in the 17th century, neighbour Sultans offered elephants as gifts to the Bornean Sultan. Current elephants would thus be non-native elephants that turned feral. On the other hand, about 15 years ago a genetic study showed that the DNA of Bornean elephants was very different from that of other Asian elephants, suggesting a very ancient separation, on the order of 300,000 years ago. However, no elephant fossils have yet been discovered in Borneo, even though fossils from other large mammals such as orang-utans have been found.
To shed light on the mystery of Bornean elephant’s origin, Chikhi and Goossens’ team used genetic data analysis and computational modelling to study the past demographic history of these animals. It is very difficult to track ancient demographic history of animals, even more when there are no fossil records to guide the work. “What we did was to create computational models for different scenarios that might have happened. 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,” explains Lounès Chikhi.