Positive selection in admixed populations from Ethiopia

Background: In the process of adaptation of humans to their environment, positive or adaptive selection has played a main role. Positive selection has, however, been under-studied in African populations, despite their diversity and importance for understanding human history. Results: Here, we have used 119 available whole-genome sequences from five Ethiopian populations (Amhara, Oromo, Somali, Wolayta and Gumuz) to investigate the modes and targets of positive selection in this part of the world. The site frequency spectrum-based test SFselect was applied to idfentify a wide range of events of selection (old and recent), and the haplotype-based statistic integrated haplotype score to detect more recent events, in each case with evaluation of the significance of candidate signals by extensive simulations. Additional insights were provided by considering admixture proportions and functional categories of genes. We identified both individual loci that are likely targets of classic sweeps and groups of genes that may have experienced polygenic adaptation. We found population-specific as well as shared signals of selection, with folate metabolism and the related ultraviolet response and skin pigmentation standing out as a shared pathway, perhaps as a response to the high levels of ultraviolet irradiation, and in addition strong signals in genes such as IFNA, MRC1, immunoglobulins and T-cell receptors which contribute to defend against pathogens. Conclusions: Signals of positive selection were detected in Ethiopian populations revealing novel adaptations in East Africa, and abundant targets for functional follow-up.

Saved in:
Bibliographic Details
Main Authors: Walsh, Sandra, Pagani, Luca, Xue, Yali, Laayouni, Hafid, Tyler-Smith, Chris, Bertranpetit, Jaume
Other Authors: Ministerio de Economía y Competitividad (España)
Format: artículo biblioteca
Published: BioMed Central 2020-10-22
Subjects:Positive selection, Selective sweeps, Human population genetics, Genomics, Admixtures, Ethiopia, West Asia, African populations,
Online Access:http://hdl.handle.net/10261/236880
http://dx.doi.org/10.13039/501100011033
http://dx.doi.org/10.13039/501100000780
http://dx.doi.org/10.13039/501100002809
http://dx.doi.org/10.13039/501100003329
http://dx.doi.org/10.13039/100004440
Tags: Add Tag
No Tags, Be the first to tag this record!