The history of the world’s smallest elephants has at all times been mysterious. First, scientists aren’t sure exactly when and the way Borneo’s pygmy elephants reached the island of Borneo from other parts of Asia. A study of their genetics in 2003 found that they’ve been genetically distinct from their closest elephant cousins for 300,000 years and could have arrived in Borneo a while later. Another hypothesis is that it’s a wild population descended from elephants introduced by humans only a couple of hundred years ago.
A brand new study published Jan. 17 within the journal Scientific Reports suggests they’ve been on Borneo for the reason that end of the Pleistocene, about 11,000 to 18,000 years ago, when Borneo was a part of a much larger landmass.
“Elephants in Borneo are much more than just an introduced population and are not descended from a few introduced individuals,” said Benoit Goossens, a wildlife biologist, director of the Danau Girang Field Center in Malaysian Borneo and co-author of the paper. “Elephants have lived there for thousands of years and come from Borneo.”
The study used long-range genetic data collected from nearly 800 DNA samples collected for the sooner study. The team then compared this information with a series of statistical models covering different historical scenarios for elephants. From this comparison, they found that elephants in Borneo went through a “genetic bottleneck” when their population dropped to low levels – and subsequently the genetic diversity of the population decreased – around 11,000 to 18,000 years ago.
The team postulates that conditions on the Earth’s surface on the time could have forced Bornean elephants beyond this genetic window. During the Pleistocene, which began greater than 2.5 million years ago and ended about 11,700 years ago, sea levels were much lower on average, and Borneo was part of a bigger land area connected to other parts of Southeast Asia.
At the top of the Pleistocene, rising sea levels began to swallow land bridges between Borneo and the islands of Java and Sumatra, in addition to the Malaysian Peninsula, that had previously allowed animal movement. According to Goossens and his colleagues’ hypothesis, when land bridges disappeared, Borneo’s elephants, not to say other large mammals, were cut off from their relatives.
Pruthu Fernando, a conservation biologist on the Sri Lanka Conservation Research Center who was not involved in the present study, called it “an excellent example of what might be explained using genetic information.”
Fernando led a 2003 study that concluded that Borneo’s elephants had diverged genetically from the Malayan and Sumatran Asian elephant (Elephas maximus) – now listed as an endangered species by the IUCN.
He also said the brand new study supports his team’s conclusions “that the Borneo elephant population is native to the island, not a feral population, and that colonization occurred throughout the Pleistocene.”
The island’s long history of elephants sends “a message that folks must be happy with elephants and feel they belong in Sabah,” Goossens said.
Their unique origins also strengthen the case for his or her conservation, Fernando added.
“The fact that this is an indigenous population and not a feral one, one of only three island populations, and a population on the fringes of the Asian elephant range makes it very important to protect it,” he said in an email, referring to the elephant subspecies inhabiting the islands of Sumatra (E. maximus sumatrensis) and Sri Lanka (E. maximus maximus). “However,” he added, “these conclusions are not new.”
John Payne, a biologist with nearly 4 a long time of experience working in Malaysian Borneo who was also not involved in the present study, said the study was “good and interesting.” However, he added that he didn’t rule out the chance that humans could have introduced elephants to the island just a couple of hundred years ago.
In 2008, Payne and several other colleagues examined historical records and located evidence that the Seventeenth-century Sultan of the Philippines could have imported several elephants from the Sulu Islands. The lineage of those animals probably comes from the Javan elephant (Elephas maximus sondaicus), which became extinct within the 18th century.
“It’s possible that the bottleneck that the population was going through actually happened in Java,” Payne said.
Still, he argued that the origins of elephants in Borneo shouldn’t influence conservation efforts.
Bornean elephants—considered by some, but not all, scientists to be a bona fide subspecies of the Asian elephant (E. maximus borneensis)—are endangered. The remaining 1,500–2,000 live mainly in a tapering patchwork of habitats wedged between oil palm plantations in northeastern Borneo. Moreover, the scourge of ivory poaching appears to have reached Borneo, with two males apparently killed for his or her tusks in 2017.
“We really need to make sure that we manage these populations very carefully,” Goossens said, “and that we stop losing males and sires from the population.”
Source: Mongabay.com with original title: “New study suggests elephants have lived in Borneo for hundreds of years”
