Vikings, merchants and pirates at the top of the world: Y-chromosomal signatures of recent and ancient migrations in the Faroe Islands.

The Faroe Islands are a small archipelago in the North Atlantic Ocean. With a current population of approximately 48,000 individuals and evidence of high levels of genetic drift, the Faroese are thought to have remained highly homogeneous since the islands were settled by Vikings around 900CE. Despite their geographic isolation, however, there is historical evidence that the Faroese experienced sporadic contact with other populations since the time of founding. Contact with Barbary pirates in the seventeenth century is documented in the Faroes; there is also the possibility of modern migrations to work in the highly productive fishery. This study set out to distinguish the signal of the original founders from later migrants. Eleven Y-chromosomal STR markers were scored for 139 Faroese males from three geographically dispersed islands. Haplotypes were analyzed using Athey's method to infer haplogroup. Median-joining networks within haplogroups were constructed to determine the phylogenetic relationships within the Faroese and between likely parental populations—Danish, Irish, and Norwegians. Dispersal patterns of individuals around Faroese haplogroups suggest different times of haplotype introduction to the islands. The most common haplogroup, R1a, consists of a large node with a tight network of neighbor haplotypes, such that 68% of individuals are one or two mutational steps away. This pattern may represent the early founder event of R1a in the Faroes. Other distributions, especially of non-Scandinavian haplotypes, document more recent introductions to the islands. The overall pattern is one of a strong founder effect followed by minor instances of later migrations.