Mitochondrial DNA patterns in the Macaronesia islands: Variation within and among archipelagos

Abstract

Macaronesia covers four Atlantic archipelagos: the Azores, Madeira, the Canary Islands, and the Cape Verde islands. When discovered by Europeans in the 15th century, only the Canaries were inhabited. Historical reports highlight the impact of Iberians on settlement in Macaronesia. Although important differences in their settlement are documented, its influence on their genetic structures and relationships has yet to be ascertained. In this study, the hypervariable region I (HVRI) sequence and coding region polymorphisms of mitochondrial DNA (mtDNA) in 623 individuals from the Azores (120) and Canary Islands (503) were analyzed. Combined with published data, these give a total of 1,542 haplotypes from Macaronesia and 1,067 from the Iberian Peninsula. The results obtained indicate that Cape Verde is the most distinctive archipelago, with an mtDNA pool composed almost exclusively of African lineages. However, the other archipelagos present an mtDNA profile dominated by the presence of West-Eurasian mtDNA haplogroups with African lineages present in varying proportions. Moreover, no signs of integration of typical Canarian U6 lineages in the other archipelagos were detected. The four Macaronesia archipelagos currently have differentiated genetic profiles, and the Azores present the highest intra-archipelago differentiation and the lowest values of diversity. The analyses performed show that the present-day genetic profile of the Macaronesian archipelagos was mainly determined by the initial process of settlement and further microdifferentiation probably as a consequence of the small population size of some islands. Moreover, contacts between archipelagos seem to have had a low impact on the mtDNA genetic pool of each archipelago.

The history of the North African mitochondrial DNA haplogroup U6 gene flow into the African, Eurasian and American continents

“…By parsimony, this would favor a sole colonization wave for the Canaries, although several waves from the same area are also possible. The fact that, even in the present day population of the Canaries, U6c1 is significantly more frequent in the eastern islands of Gran Canaria, Fuerteventura and Lanzarote [58] and the high genetic diversity found in the aboriginal colonizers of Tenerife and La Palma [6,55] seem to favor the several waves alternative. Curiously, one U6b1 lineage has been sporadically detected in a Lebanese mtDNA survey that might bring speculation about a Levantine origin for the U6b1 cluster [59].…”

“…Regarding the Canarian motif, 33% and 50% of the U6b haplotypes found respectively in mainland Portugal and Spain belong to the Canary Islands autochthonous U6b1a subgroup. Curiously, it has not been detected in the Portuguese island of Azores and Madeira or in Cape Verde either [58]. U6c is confirmed as a low-frequency Mediterranean haplogroup.…”

Continuum and variation in Creoles

“…Recent studies in human genetics have indeed brought significant insights as to the demographic impact of Sephardic Jews on the making of Cape Verde islands. Santos et al (2009) highlights DNA traces of that population in Madeira from where most of the Portuguese exiles in Cape Verde islands originated (Andrade 1996) while another study by Gonçalves et al (2003) show-cases the important contribution of the original Sephardic Jews to the genetic composition of the island of Santiago in particular. 5 Even if Sephardic Jews were a founding population (as geneticists would argue), the answer to the third question on whether the 15th-16th language they spoke left its mark on the Santiago variety today is difficult to ascertain.…”

“…As discussed below, recent studies coming from the field of Genetics (Santos et al 2009) are actually highlighting the importance of the Jewish population who originally came from Madeira and settled in Cape Verde islands. Sephardic Jews played in Senegambia in the 17th century.…”

The Genetic Makeup of Azoreans Versus Mainland Portugal Population

“…To grasp the genetic origins of mainland Portugal and Azorean populations studies on Ychromosome lineages Montiel et al, 2005;Beleza et al, 2006;Gonçalves et al, 2005;Fernando et al, 2005), mitochondrial DNA (Pereira et al, 2000b;Santos et al, 2003;Santos et al, 2005;Santos et al, 2008;Santos et al, 2010) and autosomal Alu insertion polymorphisms were performed. The nonrecombining portion of the Ychromosome retains a record of the mutational events that occurred along male lineages throughout evolution (Karafet et al, 2008).…”