Complete mitochondrial DNA sequences provide new insights into the Polynesian motif and the peopling of Madagascar

Abstract

More than a decade of mitochondrial DNA (mtDNA) studies have given the 'Polynesian motif' renowned status as a marker for tracing the late-Holocene expansion of Austronesian speaking populations. Despite considerable research on the Polynesian motif in Oceania, there has been little equivalent work on the western edge of its expansion -leaving major issues unresolved regarding the motif's evolutionary history. This has also led to considerable uncertainty regarding the settlement of Madagascar. In this study, we assess mtDNA variation in 266 individuals from three Malagasy ethnic groups: the Mikea, Vezo, and Merina. Complete mtDNA genome sequencing reveals a new variant of the Polynesian motif in Madagascar; two coding region mutations define a Malagasy-specific sub-branch. This newly defined 'Malagasy motif' occurs at high frequency in all three ethnic groups (13-50%), and its phylogenetic position, geographic distribution, and estimated age all support a recent origin, but without conclusively identifying a specific source region. Nevertheless, the haplotype's limited diversity, similar to those of other mtDNA haplogroups found in our Malagasy groups, best supports a small number of initial settlers arriving to Madagascar through the same migratory process. Finally, the discovery of this lineage provides a set of new polymorphic positions to help localize the Austronesian ancestors of the Malagasy, as well as uncover the origin and evolution of the Polynesian motif itself.

Complete mitochondrial DNA genome sequences from the first New Zealanders

“…Madagascar, like East Polynesia, was settled within the last millennium or so by peoples speaking Austronesian languages (13). Significant mtDNA variation was also indicated in a recent study of both ancient and modern mtDNA in the Gambier Islands, in French Polynesia, where new variants of the B4a1a1a haplotype were reported as well as several ancient and modern individuals with the Q1 haplotype (14).…”

Determination of population origin: a comparison of autosomal SNPs, Y-chromosomal and mtDNA haplogroups using a Malagasy population as example

“…2,3 The present population, the Malagasy, are considered an admixed population demonstrating morphological and cultural traits of Bantu and Austronesian speakers, which has been confirmed by analysis of Y-chromosomal and mitochondrial DNA (mtDNA). [4][5][6][7] The various ethnic groups on Madagascar are generally classified into two main subgroups: the Highlanders (HL), considered being more Asian in culture and phenotype, and the people from the coasts (CT), thought to be more African. 8 The determination of the phenotype, for example, eye colour, hair colour or skin colour, or the population origin from DNA has been an important research field in recent years, in which considerable progress has been accomplished (see for example [9][10][11][12][13][14][15] ).…”

Identification of Polynesian mtDNA haplogroups in remains of Botocudo Amerindians from Brazil

“…Notably, the Polynesian motif has additionally been found in Indonesian populations at low frequencies (41) and also in Madagascar (29,42).…”

“…The last scenario that we wish to assess is the possible arrival of Polynesian haplogroups to Brazil in modern times through the African slave trade from Madagascar, where 20% of the mtDNA lineages belong to the B4a1a1a haplogroup (29). In 1807 Britain outlawed the Atlantic slave trade, making it illegal for British ships to transport slaves.…”

“…One scenario is connected with the practice of the "blackbirding" trade, which occurred in 1860s and brought ∼2,000 Polynesians to Peru. The second scenario is the possible arrival of Polynesian haplogroups to Brazil in modern times through the African slave trade from Madagascar, where 20% of the mtDNA belong to the B4a1a1a haplogroup (29).…”