Institut de Biologia Evolutiva (CSIC-UPF), Universitat Pompeu Fabra, Barcelona, Catalonia, Spain
March 26, 2015 3:15, Lindbergh
The biological behavior of the Y chromosome implies that males sharing the same surname may also share a similar Y chromosome. However, socio-cultural factors, such as polyphyletism, non-paternity, adoption or matrilineal surname transmission, may disconnect transmission of the surname and from that of the Y chromosome. By genotyping 17 Y-STRs and 68 SNPs in ~2,500 male samples that carried one of 50 selected Catalan surnames we could determine sets of descendants of a common ancestor, the population of origin of the common ancestor, and the date when such a common ancestor lived. Surname frequency was positively correlated with haplotype diversity, that is, rarer surnames showed the strongest signals of coancestry. Introgression rates of Y chromosomes into a surname by non-paternity, adoption, and transmission of the maternal surname were estimated at 1.7% -2.9% per generation, with some local variation. Average ages for the founders of the surnames were estimated at ~450 years, suggesting a delay between the origin of surnames (12th-13th centuries) and the systematization of their paternal transmission. Finally, we estimate that surname prediction from a Y-chromosome haplotype, which may have interesting forensic applications, has a ~60% sensitivity but a 17% false discovery rate, and that in some cases of mispredicted surnames, the ancestors of the proband may have carried the predicted surname.
Funding was provided by the Institut d’Estudis Catalans, and by the Spanish Ministry of Economy and Innovation (grant CGL2013-44351-P)