Análise mitocondrial do genoma revela que as primeiras populações americanas eram mais geneticamente diversas

North America's First Peoples More Genetically Diverse Than Thought, Mitochondrial Genome Analysis Reveals

ScienceDaily (June 29, 2010) — The initial peopling of North America from Asia occurred approximately 15,000-18,000 years ago. However, estimations of the genetic diversity of the first settlers have remained inaccurate. In a report published online inGenome Research, researchers have found that the diversity of the first Americans has been significantly underestimated, underscoring the importance of comprehensive sampling for accurate analysis of human migrations.

New genomic research indicates that the diversity of the first Americans has been significantly underestimated. (Credit: iStockphoto/Jason Lugo)

Substantial evidence suggests that humans first crossed into North America from Asia over a land bridge called Beringia, connecting eastern Siberia and Alaska. Genetic studies have shed light on the initial lineages that entered North America, distinguishing the earliest Native American groups from those that arrived later. However, a clear picture of the number of initial migratory events and routes has been elusive due to incomplete analysis.

In this work, an international group of researchers coordinated by Antonio Torroni of the University of Pavia in Italy performed a detailed mitochondrial genome analysis of a poorly characterized lineage known as C1d. Mitochondrial DNA (mtDNA) is passed down through the maternal lineage, and mtDNA sequence markers are extremely useful tools for mapping ancestry. Similar to other haplogroups that were among the first to arrive in North America, C1d is distributed throughout the continent, suggesting that it may have been also present in the initial founding populations. However, C1d has not been well represented in previous genetic analyses, and the estimated age of approximately 7,000 years, much younger than the other founding haplogroups, was likely inaccurate.

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The initial peopling of the Americas: A growing number of founding mitochondrial genomes from Beringia

Ugo A. Perego1,2, Norman Angerhofer1, Maria Pala2, Anna Olivieri2, Hovirag Lancioni3, Baharak Hooshiar Kashani2, Valeria Carossa2, Jayne E. Ekins1, Alberto Gómez-Carballa4, Gabriela Huber5, Bettina Zimmermann5, Daniel Corach6, Nora Babudri3, Fausto Panara3, Natalie M. Myres1, Walther Parson4,
Ornella Semino2, Antonio Salas5, Scott R. Woodward1, Alessandro Achilli2,3,7,8 and Antonio Torroni2,7,8

+Author Affiliations

1Sorenson Molecular Genealogy Foundation, Salt Lake City, Utah 84115, USA;
2Dipartimento di Genetica e Microbiologia, Università di Pavia, 27100 Pavia, Italy;
3Dipartimento di Biologia Cellulare e Ambientale, Università di Perugia, 06123 Perugia, Italy;
4Unidade de Xenética, Departamento de Anatomía Patolóxica e Ciencias Forenses and Instituto de Medicina Legal, Facultade de Medicina, Universidade de Santiago de Compostela, Santiago de Compostela, Galicia 15782, Spain;
5Institute of Legal Medicine, Innsbruck Medical University, Innsbruck A-6020, Austria;
6Servicio de Huellas Digitales Genéticas, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, 1113 Buenos Aires, Argentina

↵7 These authors contributed equally to this work.

Abstract

Pan-American mitochondrial DNA (mtDNA) haplogroup C1 has been recently subdivided into three branches, two of which (C1b and C1c) are characterized by ages and geographical distributions that are indicative of an early arrival from Beringia with Paleo-Indians. In contrast, the estimated ages of C1d—the third subset of C1—looked too young to fit the above scenario. To define the origin of this enigmatic C1 branch, we completely sequenced 63 C1d mitochondrial genomes from a wide range of geographically diverse, mixed, and indigenous American populations. The revised phylogeny not only brings the age of C1d within the range of that of its two sister clades, but reveals that there were two C1d founder genomes for Paleo-Indians. Thus, the recognized maternal founding lineages of Native Americans are at least 15, indicating that the overall number of Beringian or Asian founder mitochondrial genomes will probably increase extensively when all Native American haplogroups reach the same level of phylogenetic and genomic resolution as obtained here for C1d.

Footnotes

↵8 Corresponding authors.

E-mail alessandro.achilli@unipg.it; fax 39-(075)-5855615.

E-mail antonio.torroni@unipv.it; fax 39-(0382)-528496.

[Supplemental material is available online at http://www.genome.org. The sequence data from this study have been submitted to GenBank (http://www.ncbi.nlm.nih.gov/genbank) under accession nos. HM107306–HM107368.]


Article published online before print. Article and publication date are at http://www.genome.org/cgi/doi/10.1101/gr.109231.110.
Received April 16, 2010.
Accepted May 19, 2010.
Copyright © 2010 by Cold Spring Harbor Laboratory Press

Freely available online through the Genome Research Open Access option.

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