A recent study sequenced the entire genome of mountain gorillas, providing insight into inbreeding habits and conservation.
The analysis revealed the genetic impacts associated with the now critically endangered gorillas' long-term population decline, the Wellcome Trust Sanger Institute reported.
"Mountain gorillas are among the most intensively studied primates in the wild, but this is the first in-depth, whole-genome analysis," said Chris Tyler-Smith, corresponding author from the Wellcome Trust Sanger Institute. "Three years on from sequencing the gorilla reference genome, we can now compare the genomes of all gorilla populations, including the critically endangered mountain gorilla, and begin to understand their similarities and differences, and the genetic impact of inbreeding."
In the 1980s, the population of mountain gorillas living in the Virunga volcanic mountain range, located along the borders of Rwanda, Uganda and the Democratic Republic of Congo, dropped to only about 253 as a result of habitat destruction and hunting. Since the tragic decline, conservationists have managed to get the numbers up to about 480. A genetic analysis that sought to reveal what changes would occur in such a small gene pool found a number of harmful mutations were surprisingly removed.
"This new understanding of genetic diversity and demographic history among gorilla populations provides us with valuable insight into how apes and humans, their closely related cousins, adapt genetically to living in small populations," said Aylwyn Scally, corresponding author from the Department of Genetics at the University of Cambridge. "In these data we can observe the process by which genomes are purged of severely deleterious mutations by a small population size."
The researchers looked at blood samples collected from the gorilla population over a several-year period, allowing them to sequence the entire genome of seven mountain gorillas. The analysis showed these gorillas were two or three times less genetically diverse than larger population groups found in western and central Africa. The findings also showed gorillas have been surviving in relatively small populations for thousands of years.
"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," said Yali Xue, first author from the Sanger Institute. "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."
The findings were published in a recent edition of the journal Science.
