The researchers study all the haplotypes tested but focus on the frequent mtDNA haplotypes B4a1a, E1a1a and M7c3c, which they claim support the "Out of Taiwan" model of migration.
Analysis of Hypervariable Segment I sequence variation within individual mtDNA haplogroups indicates a general decrease in the diversity of the most frequent types (B4a1a, E1a1a, M7c3c) from the Taiwanese aborigines to the Philippines and Sulawesi, although calculated standard error measures overlap for these populations.
However, as noted above with each finding the standard error for the comparisons overlapped, so the conclusions are not really meaningful.
What is interesting is the findings on the B4a1a haplotype and particularly those concerning its daughter haplotype B4a1a1, known commonly as the "Polynesian motif."
B4a1a1 is closely associated with Austronesian expansions, in my view specifically with Malayo-Polynesian expansion. While the parent haplotype B4a1a is frequent in Taiwan, the Philippines and Sulawesi, neither its predecessor B4a or the Polynesian motif B4a1a1 were found in the sample of 640 women from Taiwan.
The authors suggests that the Polynesian motif may have originated in the Philippines where it is present in small quantities in Mindanao. However they also conclude that because of the higher diversity of B4a1a in Taiwan that the haplotype must have migrated from there to the Philippines where it is found at the lower diversity. However, the estimated ages of 9,500 BP �4,600 for the haplotype in Taiwan and 7,900 BP �2,400 for the Philippines show an extensive overlap in the standard error calculation.
What seems more important is the presence of the parent B4a, which is present in small quantities in the Philippines but absent from Taiwan.
The estimated ages for the frequent haplogroups that the study focuses on i.e., 7300 BP for B4a1a, 7900 BP for E1a1a, and 11,400 BP for M7c3c, all seem to early to0 correspond to the commonly given dates for an Out of Taiwan expansion of Proto-Austronesian, which is generally place more in the range of 5000 BP.
Regards,
Paul Kekai Manansala
Sacramento
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Mol Biol Evol. 2009 Sep 15. [Epub ahead of print]
Philippine mitochondrial DNA diversity: a populated viaduct between Taiwan and Indonesia?
Tabbada KA, Trejaut J, Loo JH, Chen YM, Lin M, Miraz�n-Lahr M, Kivisild T, De Ungria MC.
DNA Analysis Laboratory, Natural Sciences Research Institute, Miranda Hall, University of the Philippines Diliman, Quezon City, Philippines.
Relatively little is known about the genetic diversity of the Philippine population, and this is an important gap in our understanding of Southeast Asian and Oceanic prehistory. Here we describe mtDNA variation in 423 Philippine samples and analyze them in the context of the genetic diversity of other Southeast Asian populations. The majority of Philippine mtDNA types are shared with Taiwanese aboriginal groups and belong to haplogroups of post-glacial and pre-Neolithic origin which have previously been identified in East Asian and Island Southeast Asian populations. Analysis of Hypervariable Segment I sequence variation within individual mtDNA haplogroups indicates a general decrease in the diversity of the most frequent types (B4a1a, E1a1a, M7c3c) from the Taiwanese aborigines to the Philippines and Sulawesi, although calculated standard error measures overlap for these populations. This finding, together with the geographical distribution of ancestral and derived haplotypes of the B4a1a sub-clade including the Polynesian Motif, is consistent with southward dispersal of these lineages "Out of Taiwan" via the Philippines to Near Oceania and Polynesia. In addition to the mtDNA components shared with Taiwanese aborigines, complete sequence analyses revealed a minority of lineages in the Philippines which share their origins - possibly dating back to the Paleolithic - with haplogroups from Indonesia and New Guinea. Other rare lineages in the Philippines have no closely related types yet identified elsewhere.
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