Genetic Change in the Polynesian Population of Easter Island: Evidence from Alu Insertion Polymorphisms

Abstract

SummaryThe origin of Pacific islanders is still an open issue in human population genetics. To address this topic we analyzed a set of 18 Alu insertion polymorphisms in a total of 176 chromosomes from native Easter Island inhabitants (Rapanui). Available genealogical records allowed us to subdivide the total island sample into two groups, representative of the native population living in the island around 1900, and another formed by individuals with some ancestors of non-Rapanui origin. Significant genetic differentiation was found between these groups, allowing us to make some biodemographic and historical inferences about the origin and evolution of this geographically isolated island population. Our data are consistent with equivalent and recent contributions from Amerindian and European migrants to the 1900s Rapanui population, with an accelerated increase in the European gene flow during the 20 th century, especially since the 1960s. Comparative analysis of our results with other available Alu variation data on neighbouring populations supports the "Voyaging Corridor" model of Polynesian human settlement, which indicates that pre-Polynesians are mainly derived from Southeast Asian and Wallacean populations rather than from Taiwan or the Philippines. This study underlines the importance of sampling and taking into account historical information in genetic studies to unravel the recent evolution of human populations.

Genome-wide Ancestry Patterns in Rapanui Suggest Pre-European Admixture with Native Americans

“…Such admixture had already been documented for Y chromosome and HLA markers for those samples [14][15][16] and is consistent with the known European history on the island beginning in AD 1722. Indeed, by the start of the slave trade in AD 1862, more than 50 ships from various European nations (Holland, Spain, England, and France) had visited the island.…”

“…During that period, trafficking in women was reported by visiting ships [43]. More recently, the Peruvian slave raids and the annexation of the island by Chile in AD 1888 connected the island even further with the outside world [14].…”

“…Moreover, in the following decade, the population continued to decline owing to diseases introduced by repatriated individuals, eventually reaching as few as 110 inhabitants ( [1], p. 167). An additional consequence of this contact was a changing genetic composition owing to increased gene flow with outside populations [14][15][16][17].…”

Further evidence of an Amerindian contribution to the Polynesian gene pool on Easter Island

“…before the Peruvian slave trades in 1862–1863. This is important because the repatriation following these slave trades entailed arrival on Easter Island of liberated slaves from different Polynesian islands and of Amerindians (9, 10). Our combined HLA data suggested, however, an even earlier introduction of the common Amerindian alleles to Easter Island, i.e.…”

Craniofacial evolution in polynesia: A geometric morphometric study of population diversity

“…Various models use genetic data to explain the origins of the Polynesians but they differ depending on whether mitochondrial DNA, y-chromosomal or autosomal data is tested. These models of dispersal include the two polar extremes of the ''Express Train'' model (Bellwood, 1991;Diamond, 1988;Green, 2003;Trejaut et al, 2005) and the opposing ''Slow Boat'' to the Bismarcks model (Capelli et al, 2001;Gonzalez-Perez et al, 2006;Kayser et al, 2000;Oppenheimer and Richards, 2001). These models contrast in their assignment of a founding population for Polynesians, the first crediting Southeast Asia, the latter suggesting more interaction between Austronesian and indigenous peoples in a voyaging corridor from Indonesia to the Bismarck Archipelago and the Solomon Islands.…”