Historical Genomes Reveal the Genomic Consequences of Recent Population Decline in Eastern Gorillas

Abstract

Many endangered species have experienced severe population declines within the last centuries. However, despite concerns about negative fitness effects resulting from increased genetic drift and inbreeding, there is a lack of empirical data on genomic changes in conjunction with such declines. Here, we use whole genomes recovered from century old historical museum specimens to quantify the genomic consequences of small population size in the critically endangered Grauer’s and mountain gorillas. We find a reduction of genetic diversity and increase in inbreeding and genetic load in the severely bottlenecked Grauer’s gorilla, whereas the small but relatively stable mountain gorilla has experienced little genomic change during the last century. These results suggest that species histories as well as the rate of demographic change may influence how population declines affect genome diversity.