García Calleja, JorgeBiagini, Simone Andrea, 1983-Cid Ibeas, Rafael deCalafell i Majó, FrancescBosch Fusté, Elena2025-05-122025-05-122025Garcia-Calleja J, Biagini SA, de Cid R, Calafell F, Bosch E. Inferring past demography and genetic adaptation in Spain using the GCAT cohort. Sci Rep. 2025 Apr 24;15(1):14225. DOI: 10.1038/s41598-025-98272-w2045-2322http://hdl.handle.net/10230/70348Located in the southwestern corner of Europe, the Iberian Peninsula is separated from the rest of the continent by the Pyrenees Mountains and from Africa by the Strait of Gibraltar. This geographical position may have conditioned distinct selective pressures compared to the rest of Europe and influenced differential patterns of gene flow. In this work, we analyse 704 whole-genome sequences from the GCAT reference panel to quantify gene flow into Spain from various historical sources and identify the top signatures of positive (adaptive) selection. While we found no clear evidence of a 16th-century admixture event putatively related to the French diaspora during the Wars of Religion, we detected signals of North African admixture matching the Muslim period and the subsequent Christian Reconquista. Notably, besides finding that well-known candidate genes previously described in Eurasians also seem to be adaptive in Spain, we discovered novel top candidates for positive selection putatively associated with immunity and diet (UBL7, SMYD1, VAC14 and FDFT1). Finally, local ancestry deviation analysis revealed that the MHCIII genomic region underwent post-admixture selection following the post-Neolithic admixture with Steppe ancestry.application/pdfeng© The Author(s) 2025. Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/.info:eu-repo/semantics/articlehttp://dx.doi.org/10.1038/s41598-025-98272-wDemographyHuman adaptationPositive selectionPost-admixture selectionSelection scanSpanish populationinfo:eu-repo/semantics/openAccess