Sunday, April 03, 2016

Orangutan Oops: Rescue Efforts Led to Genetic Mix-up Among Borneo’s Endangered Apes

Crossbreeding between subpopulations of an island’s orangutans could weaken the species, a new study finds.

The forests of Tanjung Puting National Park in southern Borneo contain some unusual orangutans that, by all rights, probably shouldn’t even exist.

Scientists say decades-old attempts to rescue, rehabilitate, and release orangutans unintentionally created an unnatural mix of genetics among the park’s orangutans that could pose future health problems for these endangered apes.

Their research was published in February in the journal Scientific Reports.

The situation dates back to the pioneering work begun in the 1970s by orangutan researchers and rescuers Biruté Galdikas and her husband, Rod Brindamour.

At that time, scientists still debated whether the orangutans living on the islands of Borneo and Sumatra were different species, something that wasn’t fully accepted until 1996.

Beyond that, what no one back then yet realized was that the orangutans living on Borneo actually represented three different subspecies, each from a different part of the island and each with widely divergent genetics.

“Bornean orangutans last shared a common ancestor around 176,000 years ago and have markedly differentiated over the last 80,000 years,” said Graham Banes, the lead author of the new paper and a scientist with Germany’s Max Planck Institute for Evolutionary Anthropology. “That’s an incredible amount of independent evolution.”

Galdikas and Brindamour rehabilitated more than 90 orangutans at their famous Camp Leakey research site and released many of them back into the national park.

The animals, most of which were rescued from the pet trade, came from all over Borneo and, we know now, were not all from the same subspecies.

At least two females released into the park came from the western portion of the island, home to a subspecies different from the orangutans that already lived in the park.