title: The history of the North African mitochondrial DNA haplogroup U6 gene flow into the African, Eurasian and American continents.
abstract: BACKGROUND
  Complete mitochondrial DNA (mtDNA) genome analyses have greatly improved the phylogeny and phylogeography of human mtDNA. Human mitochondrial DNA haplogroup U6 has been considered as a molecular signal of a Paleolithic return to North Africa of modern humans from southwestern Asia.
  
  
  RESULTS
  Using 230 complete sequences we have refined the U6 phylogeny, and improved the phylogeographic information by the analysis of 761 partial sequences. This approach provides chronological limits for its arrival to Africa, followed by its spreads there according to climatic fluctuations, and its secondary prehistoric and historic migrations out of Africa colonizing Europe, the Canary Islands and the American Continent.
  
  
  CONCLUSIONS
  The U6 expansions and contractions inside Africa faithfully reflect the climatic fluctuations that occurred in this Continent affecting also the Canary Islands. Mediterranean contacts drove these lineages to Europe, at least since the Neolithic. In turn, the European colonization brought different U6 lineages throughout the American Continent leaving the specific sign of the colonizers origin.
authors.forename: Bernard
authors.initials: B
authors.lastname: Secher
authors.forename: Rosa
authors.initials: R
authors.lastname: Fregel
authors.forename: José M
authors.initials: JM
authors.lastname: Larruga
authors.forename: Vicente M
authors.initials: VM
authors.lastname: Cabrera
authors.forename: Phillip
authors.initials: P
authors.lastname: Endicott
authors.forename: José J
authors.initials: JJ
authors.lastname: Pestano
authors.affiliation: Department of Genetics, Faculty of Biology, Universidad de La Laguna, La Laguna, Tenerife, Spain. amglez@ull.es.
authors.forename: Ana M
authors.initials: AM
authors.lastname: González
mesh_terms: D000349:Africa; D001208:Asia; D004272:DNA, Mitochondrial / Q000235:genetics*; D005060:Europe; D051456:Gene Flow; D005828:Genetics, Population; D006239:Haplotypes; D063426:Human Migration; D006801:Humans; D008969:Molecular Sequence Data; D010802:Phylogeny; D058974:Phylogeography; D017422:Sequence Analysis, DNA
chemical_list: D004272:DNA, Mitochondrial