The genomic history of the indigenous people of the Canary Islands.

The indigenous population of the Canary Islands, which colonized the archipelago around the 3rd century CE, provides both a window into the past of North Africa and a unique model to explore the effects of insularity. We generate genome-wide data from 40 individuals from the seven islands, dated between the 3rd-16rd centuries CE. Along with components already present in Moroccan Neolithic populations, the Canarian natives show signatures related to Bronze Age expansions in Eurasia and trans-Saharan migrations. The lack of gene flow between islands and constant or decreasing effective population sizes suggest that populations were isolated. While some island populations maintained relatively high genetic diversity, with the only detected bottleneck coinciding with the colonization time, other islands with fewer natural resources show the effects of insularity and isolation. Finally, consistent genetic differentiation between eastern and western islands points to a more complex colonization process than previously thought.

Mitogenomes illuminate the origin and migration patterns of the indigenous people of the Canary Islands.

The Canary Islands' indigenous people have been the subject of substantial archaeological, anthropological, linguistic and genetic research pointing to a most probable North African Berber source. However, neither agreement about the exact point of origin nor a model for the indigenous colonization of the islands has been established. To shed light on these questions, we analyzed 48 ancient mitogenomes from 25 archaeological sites from the seven main islands. Most lineages observed in the ancient samples have a Mediterranean distribution, and belong to lineages associated with the Neolithic expansion in the Near East and Europe (T2c, J2a, X3a…). This phylogeographic analysis of Canarian ancient mitogenomes, the first of its kind, shows that some lineages are restricted to Central North Africa (H1cf, J2a2d and T2c1d3), while others have a wider distribution, including both West and Central North Africa, and, in some cases, Europe and the Near East (U6a1a1, U6a7a1, U6b, X3a, U6c1). In addition, we identify four new Canarian-specific lineages (H1e1a9, H4a1e, J2a2d1a and L3b1a12) whose coalescence dates correlate with the estimated time for the colonization of the islands (1st millennia CE). Additionally, we observe an asymmetrical distribution of mtDNA haplogroups in the ancient population, with certain haplogroups appearing more frequently in the islands closer to the continent. This reinforces results based on modern mtDNA and Y-chromosome data, and archaeological evidence suggesting the existence of two distinct migrations. Comparisons between insular populations show that some populations had high genetic diversity, while others were probably affected by genetic drift and/or bottlenecks. In spite of observing interinsular differences in the survival of indigenous lineages, modern populations, with the sole exception of La Gomera, are homogenous across the islands, supporting the theory of extensive human mobility after the European conquest.

Isolation and prominent aboriginal maternal legacy in the present-day population of La Gomera (Canary Islands).

The present-day population structure of La Gomera is outstanding in its high aboriginal heritage, the greatest in the Canary Islands. This was earlier confirmed by both mitochondrial DNA and autosomal analyses, although genetic drift due to the fifteenth century European colonization could not be excluded as the main factor responsible. The present mtDNA study of aboriginal remains and extant samples from the six municipal districts of the island indeed demonstrates that the pre-Hispanic colonization of La Gomera by North African people involved a strong founder event, shown by the high frequency of the indigenous Canarian U6b1a lineage in the aboriginal samples (65%). This value is even greater than that observed in the extant population (44%), which in turn is the highest of all the seven Canary Islands. In contrast to previous results obtained for the aboriginal populations of Tenerife and La Palma, haplogroups related to secondary waves of migration were not detected in La Gomera aborigines, indicating that isolation also had an important role in shaping the current population. The rugged relief of La Gomera divided into several distinct valleys probably promoted subsequent aboriginal intra-insular differentiation that has continued after the European colonization, as seen in the present-day population structure observed on the island.

The maternal aborigine colonization of La Palma (Canary Islands).

Teeth from 38 aboriginal remains of La Palma (Canary Islands) were analyzed for external and endogenous mitochondrial DNA control region sequences and for diagnostic coding positions. Informative sequences were obtained from 30 individuals (78.9%). The majority of lineages (93%) were from West Eurasian origin, being the rest (7%) from sub-Saharan African ascription. The bulk of the aboriginal haplotypes had exact matches in North Africa (70%). However, the indigenous Canarian sub-type U6b1, also detected in La Palma, has not yet been found in North Africa, the cradle of the U6 expansion. The most abundant H1 clade in La Palma, defined by transition 16260, is also very rare in North Africa. This means that the exact region from which the ancestors of the Canarian aborigines came has not yet been sampled or that they have been replaced by later human migrations. The high gene diversity found in La Palma (95.2+/-2.3), which is one of the farthest islands from the African continent, is of the same level than the previously found in the central island of Tenerife (92.4+/-2.8). This is against the supposition that the islands were colonized from the continent by island hopping and posterior isolation. On the other hand, the great similarity found between the aboriginal populations of La Palma and Tenerife is against the idea of an island-by-island independent maritime colonization without secondary contacts. Our data better fit to an island model with frequent migrations between islands.

Mitochondrial DNA diversity in 17th-18th century remains from Tenerife (Canary Islands).

Mitochondrial DNA sequences and restriction fragment length polymorphisms were retrieved (with >80% efficiency) from a 17th-18th century sample of 213 teeth from Tenerife. The genetic composition of this population reveals an important ethnic heterogeneity. Although the majority of detected haplotypes are of European origin, the high frequency of sub-Saharan African haplotypes (15.63%), compared to that of the present-day population (6.6%), confirms the importance of the Canary Islands in the black slave trade of that epoch. The aboriginal substrate, inferred from the U6b1 haplotypes (8.59%), has also decreased due to European input. Finally, the presence of Amerindian lineages (1.5%) reveals that the Canary Islands have also received genetic flow from America.

Ancient mtDNA analysis and the origin of the Guanches.

The prehistoric colonisation of the Canary Islands by the Guanches (native Canarians) woke up great expectation about their origin, since the Europeans conquest of the Archipelago. Here, we report mitochondrial DNA analysis (HVRI sequences and RFLPs) of aborigine remains around 1000 years old. The sequences retrieved show that the Guanches possessed U6b1 lineages that are in the present day Canarian population, but not in Africans. In turn, U6b, the phylogenetically closest ancestor found in Africa, is not present in the Canary Islands. Comparisons with other populations relate the Guanches with the actual inhabitants of the Archipelago and with Moroccan Berbers. This shows that, despite the continuous changes suffered by the population (Spanish colonisation, slave trade), aboriginal mtDNA lineages constitute a considerable proportion of the Canarian gene pool. Although the Berbers are the most probable ancestors of the Guanches, it is deduced that important human movements have reshaped Northwest Africa after the migratory wave to the Canary Islands.