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The genetic structure of Pacific Islanders.

Friedlaender JS, Friedlaender FR, Reed FA, Kidd KK, Kidd JR, Chambers GK, Lea RA, Loo JH, Koki G, Hodgson JA, Merriwether DA, Weber JL - PLoS Genet. (2008)

Bottom Line: As a result, population relationships there have been open to debate.Neither of these provided an unequivocal signal of phylogenetic relations or population intermixture proportions in the Pacific.Our analysis indicates the ancestors of Polynesians moved through Melanesia relatively rapidly and only intermixed to a very modest degree with the indigenous populations there.

View Article: PubMed Central - PubMed

Affiliation: Anthropology Department, Temple University, Philadelphia, Pennsylvania, United States of America. jfriedla@temple.edu

ABSTRACT
Human genetic diversity in the Pacific has not been adequately sampled, particularly in Melanesia. As a result, population relationships there have been open to debate. A genome scan of autosomal markers (687 microsatellites and 203 insertions/deletions) on 952 individuals from 41 Pacific populations now provides the basis for understanding the remarkable nature of Melanesian variation, and for a more accurate comparison of these Pacific populations with previously studied groups from other regions. It also shows how textured human population variation can be in particular circumstances. Genetic diversity within individual Pacific populations is shown to be very low, while differentiation among Melanesian groups is high. Melanesian differentiation varies not only between islands, but also by island size and topographical complexity. The greatest distinctions are among the isolated groups in large island interiors, which are also the most internally homogeneous. The pattern loosely tracks language distinctions. Papuan-speaking groups are the most differentiated, and Austronesian or Oceanic-speaking groups, which tend to live along the coastlines, are more intermixed. A small "Austronesian" genetic signature (always <20%) was detected in less than half the Melanesian groups that speak Austronesian languages, and is entirely lacking in Papuan-speaking groups. Although the Polynesians are also distinctive, they tend to cluster with Micronesians, Taiwan Aborigines, and East Asians, and not Melanesians. These findings contribute to a resolution to the debates over Polynesian origins and their past interactions with Melanesians. With regard to genetics, the earlier studies had heavily relied on the evidence from single locus mitochondrial DNA or Y chromosome variation. Neither of these provided an unequivocal signal of phylogenetic relations or population intermixture proportions in the Pacific. Our analysis indicates the ancestors of Polynesians moved through Melanesia relatively rapidly and only intermixed to a very modest degree with the indigenous populations there.

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Global Population TreeNeighbor-joining FST-based tree for the Pacific and HGDP-CEPH combined datasets (687 microsatellites). Superimposed colors are from the STRUCTURE analysis at K = 6 (also shown).
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pgen-0040019-g005: Global Population TreeNeighbor-joining FST-based tree for the Pacific and HGDP-CEPH combined datasets (687 microsatellites). Superimposed colors are from the STRUCTURE analysis at K = 6 (also shown).

Mentions: An unrooted neighbor-joining tree for the same HGDP-CEPH and Pacific samples, excluding the indels, was calculated from a matrix of pairwise FST “coancestry” distances (similar to Reynolds' D [29], see Table S4), and is shown in Figure 5. For comparison, the cluster colors for the K = 6 STRUCTURE run were superimposed on the tree. The results were compatible with the clusters identified with STRUCTURE. Branch lengths varied inversely with values of θ̂ or expected heterozygosity, so that populations with the longest branch lengths had the lowest values of θ̂. The longest branches belonged to the Native American and separate Melanesian groups. As with the STRUCTURE results, this unrooted FST based tree had Melanesians, East Asians, and Native Americans at the opposite end of the human tree from Africans and Europeans. Trees based on other population pairwise genetic distance matrices (Nei's chord distance [30], (δμ)2 [31], the proportion of shared alleles [32], and Cavalli-Sforza and Edwards' chord distance [33]) also indicated relatively large distances between Africans and Melanesians, and also consistently placed the Taiwan Aborigines between the East Asians and Polynesians/Micronesians (Figure S2).


The genetic structure of Pacific Islanders.

Friedlaender JS, Friedlaender FR, Reed FA, Kidd KK, Kidd JR, Chambers GK, Lea RA, Loo JH, Koki G, Hodgson JA, Merriwether DA, Weber JL - PLoS Genet. (2008)

Global Population TreeNeighbor-joining FST-based tree for the Pacific and HGDP-CEPH combined datasets (687 microsatellites). Superimposed colors are from the STRUCTURE analysis at K = 6 (also shown).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2211537&req=5

pgen-0040019-g005: Global Population TreeNeighbor-joining FST-based tree for the Pacific and HGDP-CEPH combined datasets (687 microsatellites). Superimposed colors are from the STRUCTURE analysis at K = 6 (also shown).
Mentions: An unrooted neighbor-joining tree for the same HGDP-CEPH and Pacific samples, excluding the indels, was calculated from a matrix of pairwise FST “coancestry” distances (similar to Reynolds' D [29], see Table S4), and is shown in Figure 5. For comparison, the cluster colors for the K = 6 STRUCTURE run were superimposed on the tree. The results were compatible with the clusters identified with STRUCTURE. Branch lengths varied inversely with values of θ̂ or expected heterozygosity, so that populations with the longest branch lengths had the lowest values of θ̂. The longest branches belonged to the Native American and separate Melanesian groups. As with the STRUCTURE results, this unrooted FST based tree had Melanesians, East Asians, and Native Americans at the opposite end of the human tree from Africans and Europeans. Trees based on other population pairwise genetic distance matrices (Nei's chord distance [30], (δμ)2 [31], the proportion of shared alleles [32], and Cavalli-Sforza and Edwards' chord distance [33]) also indicated relatively large distances between Africans and Melanesians, and also consistently placed the Taiwan Aborigines between the East Asians and Polynesians/Micronesians (Figure S2).

Bottom Line: As a result, population relationships there have been open to debate.Neither of these provided an unequivocal signal of phylogenetic relations or population intermixture proportions in the Pacific.Our analysis indicates the ancestors of Polynesians moved through Melanesia relatively rapidly and only intermixed to a very modest degree with the indigenous populations there.

View Article: PubMed Central - PubMed

Affiliation: Anthropology Department, Temple University, Philadelphia, Pennsylvania, United States of America. jfriedla@temple.edu

ABSTRACT
Human genetic diversity in the Pacific has not been adequately sampled, particularly in Melanesia. As a result, population relationships there have been open to debate. A genome scan of autosomal markers (687 microsatellites and 203 insertions/deletions) on 952 individuals from 41 Pacific populations now provides the basis for understanding the remarkable nature of Melanesian variation, and for a more accurate comparison of these Pacific populations with previously studied groups from other regions. It also shows how textured human population variation can be in particular circumstances. Genetic diversity within individual Pacific populations is shown to be very low, while differentiation among Melanesian groups is high. Melanesian differentiation varies not only between islands, but also by island size and topographical complexity. The greatest distinctions are among the isolated groups in large island interiors, which are also the most internally homogeneous. The pattern loosely tracks language distinctions. Papuan-speaking groups are the most differentiated, and Austronesian or Oceanic-speaking groups, which tend to live along the coastlines, are more intermixed. A small "Austronesian" genetic signature (always <20%) was detected in less than half the Melanesian groups that speak Austronesian languages, and is entirely lacking in Papuan-speaking groups. Although the Polynesians are also distinctive, they tend to cluster with Micronesians, Taiwan Aborigines, and East Asians, and not Melanesians. These findings contribute to a resolution to the debates over Polynesian origins and their past interactions with Melanesians. With regard to genetics, the earlier studies had heavily relied on the evidence from single locus mitochondrial DNA or Y chromosome variation. Neither of these provided an unequivocal signal of phylogenetic relations or population intermixture proportions in the Pacific. Our analysis indicates the ancestors of Polynesians moved through Melanesia relatively rapidly and only intermixed to a very modest degree with the indigenous populations there.

Show MeSH