The genomic landscape of contemporary western Remote Oceanians

Abstract

36 The Vanuatu archipelago served as a gateway to Remote Oceania during one of the most 37 extensive human migrations to uninhabited lands, ~3,000 years ago. Ancient DNA studies 38 suggest an initial settlement by East Asian-related peoples that was quickly followed by the 39 arrival of Papuan-related populations, leading to a major population turnover. Yet, there is 40 uncertainty over the population processes and the sociocultural factors that have shaped the 41 genomic diversity of ni-Vanuatu, who present nowadays among the world’s highest linguistic 42 and cultural diversity. Here, we report new genome-wide data for 1,433 contemporary ni- 43 Vanuatu from 29 different islands, including 287 couples. We find that ni-Vanuatu derive 44 their East Asian- and Papuan-related ancestry from the same source populations and descend 45 from relatively synchronous, sex-biased admixture events that occurred ∼1,700-2,300 years 46 ago, indicating a peopling history common to all the archipelago. However, East Asian- 47 related ancestry proportions differ markedly across islands, suggesting that the Papuan-related 48 population turnover was geographically uneven. Furthermore, we detect Polynesian ancestry 49 arriving ∼600-1,000 years ago to South Vanuatu in both Polynesian- and non-Polynesian- 50 speaking populations. Lastly, we provide evidence for a tendency of spouses to carry similar 51 genetic ancestry, when accounting for relatedness avoidance. The signal is not driven by 52 strong genetic effects of specific loci or trait-associated variants, suggesting that it results 53 instead from social assortative mating. Altogether, our findings provide insight into both the 54 genetic history of ni-Vanuatu populations and how sociocultural processes have shaped the 55 diversity of their genomes. 56 57 Keywords: Pacific, populations, migrations, admixture, genetics, cultural practices 58 2 bioRxiv preprint doi: https://doi.org/10.1101/2022.01.10.475623; this version posted July 8, 2022. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC-ND 4.0 International license. 59