POLYNESIAN MITOCHONDRIAL DNAS REVEAL 3 DEEP MATERNAL LINEAGE CLUSTERS

The 4000-year-old human population expansion into Remote Oceania has b een studied from a variety of genetic perspectives. Here, we report th e discovery that Polynesians, traditionally considered to be a single cohesive linguistic and cultural unit, exhibit at least three distinct mitochondrial DNA (mtDNA) groups that probably shared a common matern al ancestor more than 85,000 years ago. The major lineage groups were first identified by PCR amplification of the mitochondrial region V de letion marker, known to be present at high frequency in Polynesian pop ulations. Sequence analysis of mtDNA hypervariable control regions rev eals a surprising number of lineages in Polynesia. We also note high s equence divergence between lineage groups deleted and not deleted in r egion V. Major group I lineages are common in Remote Oceania and inclu de about 95% of the Native Hawaiian, 90% of the Samoan, and 100% of th e Tongan donors in our sample. They contain the region V deletion and generally share three control region transition substitutions. This gr oup also contains non-Polynesian individuals, such as Indonesians, Nat ive Americans, Micronesians, Malaysians, Japanese, and Chinese. The gr oup I Polynesians differ by 4.4% in sequence identity from major linea ge group II Polynesians, who do not have the region V deletion and who share among themselves four distinct single-base substitutions. Group II individuals are seen at low frequency (< 10%) in Hawaii, Samoa, an d the Cook Islands and may represent the predominant maternal lineage group of Papuan Melanesia. Major lineage group III, not found in Hawai i, tentatively links Samoa to Indonesia. Our observation of deep mater nal genetic branches in Polynesia today confirms the notion that durin g the colonization of the Pacific, mainland Asian immigrants mixed wit h Melanesian peoples already inhabiting Near Oceania and carried a com plex assortment of maternal genotypes derived from two distinct geogra phic sources to isolated island archipelagoes.