{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,2]],"date-time":"2026-09-02T03:54:54Z","timestamp":1788321294615,"version":"build-2803163510"},"reference-count":21,"publisher":"Wiley","issue":"7","license":[{"start":{"date-parts":[[2026,7,16]],"date-time":"2026-07-16T00:00:00Z","timestamp":1784160000000},"content-version":"vor","delay-in-days":15,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"},{"start":{"date-parts":[[2026,7,1]],"date-time":"2026-07-01T00:00:00Z","timestamp":1782864000000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"content-domain":{"domain":["faseb.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["FASEB BioAdvances"],"published-print":{"date-parts":[[2026,7]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:p>\n                    The influential 2019 study by Bycroft et\u00a0al. reported remarkably pronounced ultrafine\u2010scale genetic structure within a small region of Galicia (northwestern Iberia). Using\n                    <jats:italic>fineSTRUCTURE<\/jats:italic>\n                    clustering of\n                    <jats:italic>ChromoPainter<\/jats:italic>\n                    coancestry profiles, the authors identified multiple internally coherent clusters characterized by high levels of within\u2010group haplotype sharing and reduced sharing with neighboring populations. On a broader national scale, they also reported a marked East\u2013West genetic differentiation and North\u2013South homogeneity across the Iberian Peninsula, patterns which they largely attributed to historical population movements associated with the gradual territorial expansion of Christian kingdoms between the 8th and 15th centuries following the initial Islamic conquest. Several subsequent studies have adopted similar interpretations, but all relied on the same genetic resource, the EPICOLON Phase I cohort. Following a detailed reexamination of Bycroft et\u00a0al., we identify multiple methodological issues, most notably signals consistent with unaccounted batch effects in EPICOLON, some of which were recognized by the authors in earlier studies. In contrast, we highlight recent analyses based on independent genomic datasets that consistently report high levels of genetic homogeneity within Galicia and across central and southern Iberia, with no evidence supporting a pronounced East\u2013West genetic divide across Iberia. In addition, recent studies have documented North African demographic influences in Iberia, particularly in Galicia, predating the period of Islamic rule and therefore challenging the historical interpretation proposed by Bycroft et\u00a0al. We also show that while\n                    <jats:italic>fineSTRUCTURE<\/jats:italic>\n                    is a powerful tool for detecting subtle population stratification, it may be highly sensitive to technical confounders, which can magnify or distort inferred clustering patterns. This study demonstrates that technical artifacts can strongly affect fine\u2010scale population structure inferred by\n                    <jats:italic>fineSTRUCTURE<\/jats:italic>\n                    , emphasizing the need for rigorous quality control and cautious interpretation of highly resolved genetic clusters.\n                  <\/jats:p>","DOI":"10.1096\/fba.2026-00134","type":"journal-article","created":{"date-parts":[[2026,7,16]],"date-time":"2026-07-16T14:55:49Z","timestamp":1784213749000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Challenging Patterns of Fine\u2010Scale Genetic Structure in Galicia and East\u2010to\u2010West Genetic Divergence Across the Iberian Peninsula\u2014When Technical Batches Rewrite History"],"prefix":"10.1096","volume":"8","author":[{"given":"Jacobo","family":"Pardo\u2010Seco","sequence":"first","affiliation":[{"name":"Unidade de Xen\u00e9tica, Instituto de Ciencias Forenses, Facultade de Medicina, Universidade de Santiago de Compostela, and Gen\u00e9tica de Poblaciones en Biomedicina (GenPoB) Research Group, Instituto de Investigaci\u00f3n Sanitaria (IDIS) 15706 Hospital Cl\u00ednico Universitario de Santiago (SERGAS)  Galicia Spain"},{"name":"Genetics, Vaccines and Infections Research Group (GenViP), Instituto de Investigaci\u00f3n Sanitaria de Santiago, 15706 Universidade de Santiago de Compostela Santiago de Compostela  Galicia Spain"},{"name":"Centro de Investigaci\u00f3n Biom\u00e9dica en Red de Enfermedades Respiratorias (CIBER\u2010ES)  Madrid Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Alberto","family":"G\u00f3mez\u2010Carballa","sequence":"additional","affiliation":[{"name":"Unidade de Xen\u00e9tica, Instituto de Ciencias Forenses, Facultade de Medicina, Universidade de Santiago de Compostela, and Gen\u00e9tica de Poblaciones en Biomedicina (GenPoB) Research Group, Instituto de Investigaci\u00f3n Sanitaria (IDIS) 15706 Hospital Cl\u00ednico Universitario de Santiago (SERGAS)  Galicia Spain"},{"name":"Genetics, Vaccines and Infections Research Group (GenViP), Instituto de Investigaci\u00f3n Sanitaria de Santiago, 15706 Universidade de Santiago de Compostela Santiago de Compostela  Galicia Spain"},{"name":"Centro de Investigaci\u00f3n Biom\u00e9dica en Red de Enfermedades Respiratorias (CIBER\u2010ES)  Madrid Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Conrado","family":"Mart\u00ednez\u2010Cadenas","sequence":"additional","affiliation":[{"name":"Department of Medicine Jaume I University of Castellon  Castellon Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Federico","family":"Martin\u00f3n\u2010Torres","sequence":"additional","affiliation":[{"name":"Unidade de Xen\u00e9tica, Instituto de Ciencias Forenses, Facultade de Medicina, Universidade de Santiago de Compostela, and Gen\u00e9tica de Poblaciones en Biomedicina (GenPoB) Research Group, Instituto de Investigaci\u00f3n Sanitaria (IDIS) 15706 Hospital Cl\u00ednico Universitario de Santiago (SERGAS)  Galicia Spain"},{"name":"Genetics, Vaccines and Infections Research Group (GenViP), Instituto de Investigaci\u00f3n Sanitaria de Santiago, 15706 Universidade de Santiago de Compostela Santiago de Compostela  Galicia Spain"},{"name":"Translational Pediatrics and Infectious Diseases, Department of Pediatrics 15706 Hospital Cl\u00ednico Universitario de Santiago de Compostela  Santiago de Compostela Galicia Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2336-702X","authenticated-orcid":false,"given":"Antonio","family":"Salas","sequence":"additional","affiliation":[{"name":"Unidade de Xen\u00e9tica, Instituto de Ciencias Forenses, Facultade de Medicina, Universidade de Santiago de Compostela, and Gen\u00e9tica de Poblaciones en Biomedicina (GenPoB) Research Group, Instituto de Investigaci\u00f3n Sanitaria (IDIS) 15706 Hospital Cl\u00ednico Universitario de Santiago (SERGAS)  Galicia Spain"},{"name":"Genetics, Vaccines and Infections Research Group (GenViP), Instituto de Investigaci\u00f3n Sanitaria de Santiago, 15706 Universidade de Santiago de Compostela Santiago de Compostela  Galicia Spain"},{"name":"Centro de Investigaci\u00f3n Biom\u00e9dica en Red de Enfermedades Respiratorias (CIBER\u2010ES)  Madrid Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2026,7,16]]},"reference":[{"key":"e_1_2_12_2_1","doi-asserted-by":"publisher","DOI":"10.1038\/s41467-018-08272-w"},{"key":"e_1_2_12_3_1","doi-asserted-by":"publisher","DOI":"10.1096\/fj.202502634R"},{"key":"e_1_2_12_4_1","volume-title":"La formaci\u00f3n de los dominios ling\u00fc\u00edsticos en la Pen\u00ednsula, Ib\u00e9rica","author":"Baldinger 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