Study reveals Cat Ba langurs' unique ability to drink salt water

A study by the German Primate Center—Leibniz Institute for Primate Research in Göttingen and Leipzig Zoo shows the remarkable adaptability of the critically endangered Cat Ba langurs. Despite low genetic diversity, the langurs have retained key genetic traits that help them survive in their isolated environment on Cat Ba Island in Vietnam. One of these remarkable adaptations is the ability to drink salt water.
The study is dedicated to the genetic challenges faced by the fewer than 100 remaining individuals of this primate species. Due to the dramatic decline of its population, the species suffers from genetic impoverishment, high inbreeding and a potentially increased susceptibility to disease. Nevertheless, analysis of their genetic information shows that genetic diversity has been maintained in functionally important areas of their genetic information. This enables the Cat Ba langurs (Trachypithecus poliocephalus) to continue to cope adequately with changing environmental conditions.
"Their adaptability makes the animals unique. Drinking salt water is an outstanding example of this," says Liye Zhang, geneticist at the German Primate Center (DPZ) and lead author of the study.
This extraordinary ability is a direct consequence of their isolated island home, where there are only limited freshwater sources. The researchers show that changes in certain genes have probably increased tolerance to salt water. These genetic adaptations enable langurs to cope with the high sodium content of salt water and thus contribute to their survival in this unique environment.
The research is in the journal Nature Communications.

The Cat Ba langur: A symbol of adaptability with urgent need for protection
The Cat Ba langur, one of the rarest primate species in the world, is not only highly endangered, but also symbolizes nature's remarkable ability to adapt to challenging conditions. "These research results highlight the urgency of better protecting the Cat Ba langur and its habitat," emphasizes Christian Roos, scientist at the DPZ and co-author of the current study.
Although many mammal populations are declining worldwide, the genetic effects of such population declines often remain unexplored. The Cat Ba langur is a valuable model for analyzing the consequences of severe population declines on the genetic diversity of a species. The population of this langur species once numbered several hundred animals, but was reduced to an alarming 40 individuals by 2004 due to hunting, poaching and habitat loss.
The population has since recovered to around 85 animals. Nevertheless, the species is still threatened with extinction, particularly due to habitat fragmentation, disturbance from uncontrolled tourism and increasing inbreeding. These threats underline the need to expand existing conservation measures and intensify targeted conservation programs in order to ensure the long-term survival of this primate species.
More information: Liye Zhang et al, Genomic adaptation to small population size and saltwater consumption in the critically endangered Cat Ba langur, Nature Communications (2024).
Journal information: Nature Communications
Provided by The German Primate Center