"According to a New York Times report, migrants from North Africa first arrived in the Canary Islands around A.D. 100, and inhabited all seven of the islands by A.D. 1000 at the latest. The study, conducted by population geneticist Rosa Fregel of the University of La Laguna and her colleagues, examined human mitochondrial DNA recovered from skeletons unearthed at 25 sites scattered over all of the Canary Islands, which are located off the coast of Morocco. “In the Canary Islands indigenous people, we find typical North African lineages, but also some other lineages with a Mediterranean distribution, and also some lineages that are of sub-Saharan African origin,” Fregel said. The researchers also found four new lineages unique to Gran Canaria and two of the eastern islands, suggesting there may have been at least two waves of migration, one of which was large enough to result in a great deal of genetic diversity. Europeans who traveled to the islands in the 1400s claimed the Canarians lacked navigational skills, leading to the suggestion that they may have been brought to the islands by Romans or Carthaginians. "

This is the paper:
Rosa Fregel et al-

"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 (1stmillennia 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."

It's also discussed here.

"Numerous studies of the culture and genetics of indigenous people living in the Canary Islands, an archipelago off the coast of Morocco, point to North African Berbers as the founders, but more recent human activities -- such as the Spanish conquest, the start of sugarcane plantations and the slave trade -- have changed the indigenous population's genetic makeup. To shed light on who first colonized the archipelago, researchers analyzed 48 ancient mitochondrial genomes from 25 archaeological sites across the seven main islands. They selected mitochondrial genomes because, since they are inherited directly from the mother, they are especially consistent and useful for tracking human migrations."