Over the sands and far away: Interpreting an Iberian mitochondrial lineage with ancient Western African origins

Abstract

There is a continuous effort for characterizing the genetic links between Africa and Europe, mostly using lineages and haplotypes th at are specific to one continent but had an ancient origin in the other. Mitochondrial DNA has been proven to be a very useful tool for this purpose since a high number of putatively European-specific variants of the African L* lineages have been defined over the years. Complete mitochondrial sequences reveal that as much as 65% of these can be the product of recent introgressions, while the remaining 35% hint to pre-Neolithic population movements over the Strait of Gibraltar. Due to their geographic position, Spain and Portugal seem to be ideal places for searching for these lineages. However, micro-differentiation patterns across the Iberian Peninsula make their frequency geographically uneven. Five members of a minor branch of haplogroup L3f have been found in recent DNA samplings in the region of Asturias (Northern Spain), which is noteworthy for its historical isolation. Its frequency in the population (≈1%) is unexpectedly high in comparison with other related lineages in Europe. Complete mitochondrial DNA sequencing, phylogenetic and phylogeographic analyses, yield results concordant with a previously proposed Neolithic connection between Southern Europe and Western Africa, which might be key to the proper understanding of the ancient links between these two continents.