Past Connectivity but Recent Inbreeding in Cross River Gorillas Determined Using Whole Genomes from Single Hairs

Area of Science:

• Genomics
• Primate Conservation
• Evolutionary Biology

Background:

• Western gorillas (Gorilla gorilla) comprise two subspecies: western lowland and Cross River gorillas.
• Limited genomic data exists for Cross River gorillas due to sampling challenges, hindering population-level studies.

Purpose of the Study:

• To expand the genomic data for wild western gorillas, focusing on the critically endangered Cross River gorilla.
• To analyze population structure, genetic diversity, and evolutionary history of Cross River gorillas using whole genome sequencing.

Main Methods:

• Whole genome sequencing of 41 new samples from wild western gorillas, including 25 Cross River gorillas, using DNA from shed hairs.
• Integration of new genomes with existing public data for comprehensive population genomic analyses.

Main Results:

• Confirmation of three distinct population clusters within Cross River gorillas with low genome-wide heterozygosity.
• Identification of long runs of homozygosity (>10 Mb) indicating recent inbreeding and a recent bottleneck in Cross River gorillas.
• Detection of past gene flow between Cross River gorilla sites and with northern western lowland gorillas and eastern gorillas.

Conclusions:

• This study pioneers whole genome sequencing from single shed hairs in a wild species.
• Genomic insights underscore the urgent need for conservation strategies to improve connectivity among Cross River gorilla populations.