Mountain gorilla genomes reveal the impact of long-term population decline and inbreeding

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Science  10 Apr 2015:
Vol. 348, Issue 6231, pp. 242-245
DOI: 10.1126/science.aaa3952

Genomes in the mist

The mountain gorilla is an iconic species that is at high risk of extinction. Xue et al. have sequenced 13 gorillas from two different populations to probe their genetic diversity. The genomes show large tracts of homozygosity and the loss of highly deleterious genetic variants, indicating population bottlenecks and inbreeding. This loss of genetic diversity appears to have started over 20,000 years ago and may have been caused by changes in climate and human-associated effects.

Science, this issue p. 242


Mountain gorillas are an endangered great ape subspecies and a prominent focus for conservation, yet we know little about their genomic diversity and evolutionary past. We sequenced whole genomes from multiple wild individuals and compared the genomes of all four Gorilla subspecies. We found that the two eastern subspecies have experienced a prolonged population decline over the past 100,000 years, resulting in very low genetic diversity and an increased overall burden of deleterious variation. A further recent decline in the mountain gorilla population has led to extensive inbreeding, such that individuals are typically homozygous at 34% of their sequence, leading to the purging of severely deleterious recessive mutations from the population. We discuss the causes of their decline and the consequences for their future survival.

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