Ferrando-Bernal, Manuel, 1990-Morcillo Suárez, Carlos, 1969-de Dios, ToniGelabert Xirinachs, Pere, 1991-Civit, SergiDíaz Carvajal, AntoniaOllich Castanyer, ImmaAllentoft, Morten E.Valverde, SergiLalueza Fox, Carles, 1965-2021-03-172021-03-172020Ferrando-Bernal M, Morcillo-Suarez C, De-Dios T, Gelabert P, Civit S, Díaz-Carvajal A, Ollich-Castanyer I, Allentoft ME, Valverde S, Lalueza-Fox C. Mapping co-ancestry connections between the genome of a Medieval individual and modern Europeans. Sci Rep. 2020; 10(1):6843. DOI: 10.1038/s41598-020-64007-22045-2322http://hdl.handle.net/10230/46810Historical genetic links among similar populations can be difficult to establish. Identity by descent (IBD) analyses find genomic blocks that represent direct genealogical relationships among individuals. However, this method has rarely been applied to ancient genomes because IBD stretches are progressively fragmented by recombination and thus not recognizable after few tens of generations. To explore such genealogical relationships, we estimated long IBD blocks among modern Europeans, generating networks to uncover the genetic structures. We found that Basques, Sardinians, Icelanders and Orcadians form, each of them, highly intraconnected sub-clusters in a European network, indicating dense genealogical links within small, isolated populations. We also exposed individual genealogical links -such as the connection between one Basque and one Icelandic individual- that cannot be uncovered with other, widely used population genetics methods such as PCA or ADMIXTURE. Moreover, using ancient DNA technology we sequenced a Late Medieval individual (Barcelona, Spain) to high genomic coverage and identified IBD blocks shared between her and modern Europeans. The Medieval IBD blocks are statistically overrepresented only in modern Spaniards, which is the geographically closest population. This approach can be used to produce a fine-scale reflection of shared ancestry across different populations of the world, offering a direct genetic link from the past to the present.application/pdfeng© The Author(s) 2020. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, 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 license, and indicate if changes were made. Te images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license 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 license, visit http://creativecommons.org/licenses/by/4.0/.info:eu-repo/semantics/articlehttp://dx.doi.org/10.1038/s41598-020-64007-2EvolutionMolecular biologyinfo:eu-repo/semantics/openAccess