Rare-looking monkey in Borneo may be a hybrid and scientists are concerned

Tour guide Brenden Miles was in the Malaysian part of Borneo when he noticed a unique-looking monkey six years ago. Hence, he snapped a few photos of the primate.

“At first, I thought it could be a morph of the silvered leaf monkey,” Miles said via Science News, explaining the monkey may just have a rare color variation, but also noticing other details that were different. “Its nose was long like that of a proboscis monkey, and its tail was thicker than that of a silvered leaf [monkey].”

Now that photo of that monkey is believed to be a hybrid of two distant, but related primate species sharing the same habitat.

A male proboscis monkey (Nasalis larvatus) and a female silvered leaf monkey (Trachypithecus cristatus) mated with each other, creating the hybrid primate, according to Science News. Hence, scientists are worried about the hybridization of the two species.

Hybridization is already examined between related species. “But hybridization across genera, that’s very rare,” said Ramesh Boonratana, who specializes in primates as Southeast Asia for the International Union for Conservation of Nature’s vice-chair.

Primatologist Nadine Ruppert believes the “Severe habitat loss, fragmentation and degradation” all caused by oil plantations cause the hybridization, Science News reported.

“Different species — even from the same genus — when they share a habitat, they may interact with each other, but they may usually not mate. This kind of cross-genera hybridization happens only when there is some ecological pressure,” Ruppert said.

“In certain areas, both [monkey] species are confined to small forest fragments along the river,” Ruppert added. “The animals cannot disperse and, in this case, the male of the larger species — the proboscis monkey — can easily displace the male silvered leaf monkey.”