A population history of Tokelau – genetic variation and change in atoll populations

Abstract

Tokelau is a remote archipelago of atolls in western Polynesia, located approximately 500 km north of Samoa. It is thought to have been settled as part of the Austronesian expansion(s). However, its exact role in this population dispersal is not completely understood. Here we describe the results of complete mitochondrial genome sequencing for both the current inhabitants and ancient individuals from the archipelago in addition to an assessment of Y-chromosome diversity among the present population. We find relatively little genetic diversity compared with other western Polynesian populations, most likely due to historically reported bottleneck events. However, the presence of rare mitochondrial lineages hints at prehistoric occupation by peoples from the northwest (e.g., Tuvalu and Micronesia). Ancient DNA data from Atafu, the northernmost Tokelauan atoll, is further consistent with abandonment and later resettlement of the island from a Samoan or Samoan-derived source population. Moreover, the ancient and modern mitogenomes also suggest links with other atoll populations in the western Pacific.

Keywords:

• Pacific
• Tokelau
• ancient DNA
• migration
• mtDNA
• Y-chromosome

Acknowledgements

We offer our sincere thanks to the Tokelauan communities of Atafu, Nukunonu, and Fakaofo for providing genetic samples, genealogical information, and support for this study, and to the Atafu community for allowing ancient DNA analysis on the archaeological human remains recovered from excavations on their island. We also thank those at the Kosrae Historic Preservation Trust for allowing genetic analysis to be undertaken on the ancient samples from Kosrae. Thanks to the Allan Wilson Centre for providing a summer studentship scholarship for Edana Lord, who worked on the modern mitochondrial data generation. Our thanks to Judith Huntsman for comments on the manuscript and to Keli Kalolo and the Taupulega of Atafu for their support of this study and its publication. Additional thanks to the two anonymous reviewers for their constructive feedback.

Additional information

Funding

Funding for this research was provided to EM-S by National Geographic’s Genographic Project for the modern DNA studies and to DA and others from NSF grant #0849407 for archaeological excavations in Tokelau. Funding for the aDNA work was provided to EM-S by the Department of Anatomy.