Exploring sex-biased genomic signals in Fulani: a key population to unveil the African Sahel peopling history

The Sahel region, situated between the Sahara Desert to the north and the tropical forests to the south, is a heterogeneous ecosystem that acted as a corridor for multiple human migrations between Western and Eastern Africa. In this region live the Fulani, the largest pastoral nomadic group in the world, amounting to almost 40 million people, one-third of whom maintain a nomadic lifestyle. It has been recently proposed that the Fulani ancestry includes a relevant non sub-Saharan genetic component due to admixture events among populations migrating to the Green Sahara during its last humid phase (12,000-5,000 BP). Despite dilution in other descendant populations, this genetic component remains prominent within the Fulani probably as a consequence of their endogamous practices, making them crucial for understanding the peopling of Africa. This project aims to investigate possible sex-biased genetic patterns among the Fulani through the comparison of genomic signatures in the autosomes and the X chromosome. To this aim, 43 modern samples (including 23 Fulani) were analysed by high-coverage whole-genome sequencing. These data were merged with both modern and ancient DNA samples from the public Allen Ancient DNA Resource, for a total of 2,389 samples from Africa, Europe and the Middle East. Genotypes for 921,863 SNPs (896,901 from the autosomes and 24,962 from the X chromosome) were used to obtain PCA, ADMIXTURE analysis and outgroup-f3 statistics. Our preliminary results support the hypothesis that Fulani are descendants of a ghost Green Sahara population. Although no strong signals of sex bias were found, our data show a clear pattern due to the intrinsic structure of the Fulani population, providing insight into the complex dynamics that have shaped genetic variability in the Sahel region.