Evolutionary genomics of gorillas: from ghost introgession to recent dispersal

Population genetics addresses evolutionary change in populations through time. Here we take a multifaceted approach to uncover the evolutionary history of gorillas. Firstly, we modelled the demographic history of gorillas using high-coverage, whole genome sequences from all four extant subspecies. We infer that up to 3% of the genomes of eastern gorillas are introgressed from a previously unknown, extinct population which diverged from the common ancestor of all extant gorillas more than 3 million years ago. Taken together with previous results in humans and bonobos this illustrates the prevalence of archaic admixture in the great apes. We infer that the ghost introgression event likely had functional consequences for bitter taste perception in eastern gorillas. Secondly, we analysed exome sequences derived from wild gorilla faecal and hair samples, which represents the densest sampling of wild gorilla populations to date. We explored signatures of local adaptation between the gorilla subspecies. Novel signatures of positive selection were not detectable due to an experimental issue in the target capture hybridisation. Nonetheless, with this novel dataset we can recapitulate known trends in gorilla diversity. Moreover, we uncover differential dispersal patterns between the subspecies via analysis of the exome of chromosome X, which had previously only been observed in field studies not in genetic data. The work of this thesis thus refines our understanding of gorilla evolution, adding new insights in deep evolutionary time and recent dispersal.