Matrilineal diversity and population history of Norwegians

Abstract

Background While well known for its Viking past, Norway's population history and the influences that have shaped its genetic diversity are less well understood. This is particularly true with respect to its demography, migration patterns, and dialectal regions, despite there being curated historical records for the past several centuries. In this study, we undertook an analysis of mitochondrial DNA (mtDNA) diversity within the country to elaborate this history from a matrilineal genetic perspective. Methods We aggregated 1174 partial modern Norwegian mtDNA sequences from the published literature and subjected them to detailed statistical and phylogenetic analysis by dialectal regions and localities. We further contextualized the matrilineal ancestry of modern Norwegians with data from Mesolithic, Iron Age, and historic period populations. Results Modern Norwegian mtDNAs fell into eight West Eurasian (N, HV, JT, I, U, K, X, W), five East Eurasian (A, F, G, N11, Z), and one African (L2) haplogroups. Pairwise analysis of molecular variance (AMOVA) estimates for all Norwegians indicated they were differentiated from each other at 1.68% (p < 0.001). Norwegians within the same dialectal region also showed genetic similarities to each other, although differences between subpopulations within dialectal regions were also observed. In addition, certain mtDNA lineages in modern Norwegians were also found among prehistoric and historic period populations, suggesting some level of genetic continuity over hundreds to many thousands of years. Conclusions This analysis of mtDNA diversity provides a detailed picture of the genetic variation within Norway in light of its topography, settlement history, and historical migrations over the past several centuries.

Phylogeographic history of mitochondrial haplogroup J in Scandinavia

“…This frequency is quite similar to that seen in modern-day Scandinavian populations, despite statistical differences in the frequencies of other haplogroups (Krzewi nska et al, 2015). Today, haplogroup J is currently the third most common maternal lineage in Norway (Kristjansson et al, 2021), and, overall, the fourth most common in Sweden (Simoni et al, 2000) and modern-day Europe (Rishishwar & Jordan, 2017;Simoni et al, 2000). This intriguing distribution of haplogroup J coupled with the gap in knowledge regarding the dispersal of haplogroup J along migrations routes with respect to Scandinavia motivated an exploration of the pattern of genomic variation in haplogroup J and the timing of its dispersal into Scandinavia.…”

“…Of these lineages, haplogroup J has a relatively uniform distribution across Europe and the Near East, making up about 6%–22% of the mtDNAs in modern populations from these regions (Kristjansson et al, 2021 ; Lappalainen et al, 2009 ; Lembring et al, 2013 ; Pliss et al, 2006 ; Simoni et al, 2000 ; Vidrová et al, 2008 ). More specifically, haplogroup J is found at a moderate frequency among the English and Welsh (15.2%–21.7%) in Western Europe (Richards et al, 1996 ; Richards et al, 2000 ), while its frequencies among Mazandarani populations near the Caspian Sea and the Iraqi population in the East are between 15% and 18% (Al‐Zahery et al, 2003 ; Metspalu et al, 2004 ; Quintana‐Murci et al, 2004 ; Richards et al, 2000 ).…”

The mitochondrial DNA constitution shaping T-cell immunity in patients with rectal cancer at high risk of metastatic progression

“…We observed a clear arrangement of mtDNA haplogroups in this population-based rectal cancer cohort from Norway. The 22 patients harbouring the common H haplogroup [ 33 ], the most recent addition to European mtDNAs [ 34 , 35 ], had TVN of 29 or below (except one case with TVN of 32), while the 20 patients with other European haplogroups and the two Asian haplogroup cases had TVN above the median value (of whom all but four had TVN of 36 or higher; Fig. 1 ).…”

Evolution and dispersal of mitochondrial DNA haplogroup U5 in Northern Europe: insights from an unsupervised learning approach to phylogeography

“…These Neolithic maternal lineages did not extend as successfully far north, where U5 comprises over 50% of maternal lineages among the Saami. Among Finns and Scandinavians, U5 continues to be the second-most frequent haplogroup after H [ 30 , 31 , 33 ].…”

“…Its frequency varies particularly widely within Northern Europe. Haplogroup U5 mtDNAs are present in northern Saami populations at over 50% [ 30 – 32 ], while their corresponding frequencies in the southern areas of the Scandinavian countries (Norway, Sweden, and Denmark) lie between 6–15% [ 31 , 33 , 34 ]. These differing frequencies raise interesting questions about the phylogenetic structure of this major lineage and the timing of the dispersal of its subbranches within the European continent.…”