Research Article: Indian Ocean Crossroads: Human Genetic Origin and Population Structure in the Maldives

Date Published: May 21, 2013

Publisher: Blackwell Publishing Ltd

Author(s): Jeroen Pijpe, Alex Voogt, Mannis Oven, Peter Henneman, Kristiaan J Gaag, Manfred Kayser, Peter Knijff.

http://doi.org/10.1002/ajpa.22256

Abstract

The Maldives are an 850 km-long string of atolls located centrally in the northern Indian Ocean basin. Because of this geographic situation, the present-day Maldivian population has potential for uncovering genetic signatures of historic migration events in the region. We therefore studied autosomal DNA-, mitochondrial DNA-, and Y-chromosomal DNA markers in a representative sample of 141 unrelated Maldivians, with 119 from six major settlements. We found a total of 63 different mtDNA haplotypes that could be allocated to 29 mtDNA haplogroups, mostly within the M, R, and U clades. We found 66 different Y-STR haplotypes in 10 Y-chromosome haplogroups, predominantly H1, J2, L, R1a1a, and R2. Parental admixture analysis for mtDNA- and Y-haplogroup data indicates a strong genetic link between the Maldive Islands and mainland South Asia, and excludes significant gene flow from Southeast Asia. Paternal admixture from West Asia is detected, but cannot be distinguished from admixture from South Asia. Maternal admixture from West Asia is excluded. Within the Maldives, we find a subtle genetic substructure in all marker systems that is not directly related to geographic distance or linguistic dialect. We found reduced Y-STR diversity and reduced male-mediated gene flow between atolls, suggesting independent male founder effects for each atoll. Detected reduced female-mediated gene flow between atolls confirms a Maldives-specific history of matrilocality. In conclusion, our new genetic data agree with the commonly reported Maldivian ancestry in South Asia, but furthermore suggest multiple, independent immigration events and asymmetrical migration of females and males across the archipelago. Am J Phys Anthropol 151:58–67, 2013. © 2013 Wiley Periodicals, Inc.

Partial Text

We report a strong genetic link between the Maldives Islands and the Indian sub-continent. We exclude the sharing of haplogroups between Southeast Asia and the Maldives, which questions the previously suggested central role of a Maldive Islands’ stopping point for migration from South East Asia to Madagascar. The Maldives were more likely used for supplies than for settling a population, which is no surprise considering the limited landmass of coral atolls. We also dismiss female-mediated gene flow from West Asia. Male-mediated gene flow from West Asia to the Maldives could have occurred, although it cannot be separated from such gene flow through South Asia. The wide range of Y-chromosomal and mtDNA haplogroups mirrors the haplogroup diversity in South Asia. We find a subtle substructure within the Maldives that is not directly related to geographic distance or dialect. Reduced diversity of Y-chromosomal markers on each atoll combined with reduced male-mediated gene flow between atolls suggests independent founder effects for each atoll. Reduced female-mediated gene flow between atolls confirms a Maldives-specific history of matrilocality.

 

Source:

http://doi.org/10.1002/ajpa.22256

 

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