Genetic architecture of dusunic, murutic and paitanic ethnic groups of Sabah, Malaysia as revealed by high density genotyping arrays
The native ethnic groups of Sabah are categorized under the 'North Borneo' stock of the Austronesian linguistic family. It is generally believed that the native groups of Northern Borneo are plausibly descendants of the 'Out-of-Taiwan' Austronesian wave of human migration. Whi...
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| Format: | Thesis |
| Language: | English |
| Published: |
2016
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| Subjects: | |
| Online Access: | http://eprints.ums.edu.my/17809/ http://eprints.ums.edu.my/17809/1/Genetic%20architecture%20of%20dusunic.pdf |
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| Summary: | The native ethnic groups of Sabah are categorized under the 'North Borneo' stock
of the Austronesian linguistic family. It is generally believed that the native groups
of Northern Borneo are plausibly descendants of the 'Out-of-Taiwan' Austronesian
wave of human migration. While there may be some anthropological evidence
support for this, the lack of genetic evidence makes the hypothesis inconclusive. As
such, this study aimed to unravel and compare the population metrics, genetic
structure and genetic relationships of the Northern Borneo indigenous ethnic
groups (North Borneans) against Southern China and Southeast Asian populations,
and subsequently provide inference of their migration history. Ethical clearance was
obtained and blood samples were collected from healthy individuals. A total of 117
individuals representing five indigenous ethnic groups namely Dusun, Rungus,
Sonsogon, Sungai-Lingkabau and Murut-Paluan were genotyped with -2.4 million
genome-wide single nucleotide polymorphism (SNP) markers. The genotype data
were then merged with public datasets i. e. HapMap, Human Genome Diversity
Project (HGDP), Singapore Genome Variation Project (SGVP), and Pan-Asian SNP
Consortium( PASNP) data to form a comprehensive meta-data set composing of 89
regional and worldwide populations. Population metrics namely decay of linkage
disequilibrium, genetic heterozygosity, genetic differentiation (FsT) and phylogeny
were analyzed. Next, comparative population genetic structure analysis was
performed to determine the genetic gradient among populations, and to assign
genetic component and its admixture across the tested populations. Finally, the
genetic relationships among populations were inferred by a combinatorial
correlation of these outputs. The results showed that the North Borneans were
subdivided into three subgroups which were 'Dusun-Rungus', 'Sonsogon-Sungai',
and 'Muruts'. The 'Sonsogon-Sungagi' rouping, which is made up of Dusunic and
Paitanic-speakingg roup respectively,indicated that the linguistic groupings of the
ethnic groups do not necessarily reflect their genetic affinity. Meanwhile,t he North
Borneans had reduced heterozygosity and were highly differentiated among
themselves. Clustering with principal components clearly depicted that each ethnic
group is an independent genetic entity. As a whole, they formed a unique genetic
ancestry, which was not found in previous reports. Importantly, they were closest
to the non-Negrito Filipinos and the Cosmopolitan Malays of Singapore. However,
phylogenetic analysis clustered the North Borneans to the Filipinos and Taiwan
Natives, but not to other Island Southeast Asians. On the contrary, the Bidayuhs
(West Borneo) was clustered with the Javanese and Temuans. Subsequent
estimation of gene flow direction revealed that statistically probable migration
event(s) was unidirectional, from North Borneo towards mainland Southeast Asia,
but not the reverse. As such, a new hypothesis is postulated that the five ethnic
groups descended from Taiwan Natives and Borneo Island served as one of the
cross-road for two distinct waves of migration from mainland Southeast Asia and
Taiwan, respectively. In conclusion, the findings indicated that Sabah's indigenous
population, as a whole, has a unique yet distinctive pool of genetic variants, which
are important for anthropological and medical genetic studies |
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