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Open Access Research article

A new deep branch of eurasian mtDNA macrohaplogroup M reveals additional complexity regarding the settlement of Madagascar

François-X Ricaut12*, Harilanto Razafindrazaka1, Murray P Cox3, Jean-M Dugoujon1, Evelyne Guitard1, Clement Sambo4, Maru Mormina5, Marta Mirazon-Lahr5, Bertrand Ludes16 and Eric Crubézy1

Author Affiliations

1 CNRS FRE 2960, Laboratoire d'Anthropobiologie, Université de Toulouse, Toulouse III Paul sabatier, 37 allées Jules Guesde, 31073 Toulouse cedex 3, France

2 Center for Archaeological Sciences, Katholieke Universiteit Leuven, Celestijnenlaan 200E, 3001 Heverlee, Belgium

3 Institute of Molecular BioSciences, Allan Wilson Centre for Molecular Ecology and Evolution, and the Bio-Protection Centre, Massey University, Palmerston North 4442, New Zealand

4 Ecole Normale Supérieure, Université de Toliara, Toliara, Madagascar

5 Leverhulme Centre for Human Evolutionary Studies, Henry Wellcome Building, Fitzwilliam Street, University of Cambridge, Cambridge CB2 1QH, UK

6 Laboratoire d'Anthropologie Moléculaire, Institut de Médecine Légale, 11 rue Humann, 67085 Strasbourg, France

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BMC Genomics 2009, 10:605  doi:10.1186/1471-2164-10-605

Published: 14 December 2009

Abstract

Background

Current models propose that mitochondrial DNA macrohaplogroups M and N evolved from haplogroup L3 soon after modern humans left Africa. Increasingly, however, analysis of isolated populations is filling in the details of, and in some cases challenging, aspects of this general model.

Results

Here, we present the first comprehensive study of three such isolated populations from Madagascar: the Mikea hunter-gatherers, the neighbouring Vezo fishermen, and the Merina central highlanders (n = 266). Complete mitochondrial DNA genome sequences reveal several unresolved lineages, and a new, deep branch of the out-of-Africa founder clade M has been identified. This new haplogroup, M23, has a limited global distribution, and is restricted to Madagascar and a limited range of African and Southwest Asian groups.

Conclusions

The geographic distribution, phylogenetic placement and molecular age of M23 suggest that the colonization of Madagascar was more complex than previously thought.