• H2020
• Excellent Science
• European Research Council

The first project to sequence whole genomes from mountain gorillas reveals that many harmful genetic variations have been removed from the population through inbreeding.

The research also shows that mountain gorillas are genetically adapting to surviving in small populations and that they have survived in small numbers for thousands of years.

The project, which received funding from the European Research Council (ERC) and was partly led by the University of California Davis School of Veterinary Medicine, USA, has given scientists and conservationists an insight into the impact of population decline on these critically endangered apes. The study also provides clues as to how apes and humans (their closely related cousins) adapt genetically to living in small populations.

The ‘Gorilla Doctors’ provided blood samples for the study, enabling researchers to sequence the whole genomes of seven mountain gorillas for the first time. The scientists found that mountain gorillas, along with eastern lowland gorillas (their closely related neighbours) were two to three times less genetically diverse than gorillas from larger groups in western regions of central Africa. While there are concerns that this low level of genetic diversity may make the mountain gorillas more vulnerable to environmental change and to disease, including cross-infectious strains of human viruses, the researchers were surprised to find that inbreeding has been, in some ways, genetically beneficial.

Fewer harmful loss-of-function variants were found in the mountain gorilla population than in the more numerous western gorilla populations. These variants stop genes from working and can cause serious, often fatal, health conditions. By analysing the variations in each genome, researchers also discovered that mountain gorillas have survived in small numbers for thousands of years.

Commenting, Yali Xue, first author from the Wellcome Trust Sanger Institute, which also part funded the research, said: “We worried that the dramatic decline in the 1980s would be catastrophic for mountain gorillas in the long term, but our genetic analyses suggest that gorillas have been coping with small population sizes for thousands of years.

“While comparable levels of inbreeding contributed to the extinction of our relatives the Neanderthals, mountain gorillas may be more resilient. There is no reason why they should not flourish for thousands of years to come.”

Scientists hope the whole-genome sequence data will aid conservation efforts. The research is published in the journal Science.