Tracing the genetic legacy in the French Caribbean islands: A study of mitochondrial and Y‐chromosome lineages in the Guadeloupe archipelago

Abstract

Objectives: The history of the Caribbean region is marked by numerous and various successive migration waves that resulted in a global blending of African, European, and Amerindian lineages. As the origin and genetic composition of the current population of French Caribbean islands has not been studied to date, we used both mitochondrial DNA and Y-chromosome markers to complete the characterization of the dynamics of admixture in the Guadeloupe archipelago. Materials and Methods: We sequenced the mitochondrial hypervariable regions and genotyped mitochondrial and Y-chromosomal single nucleotide polymorphisms (SNPs) of 198 individuals from five localities of the Guadeloupe archipelago.Results: The maternal haplogroups revealed a blend of 85% African lineages (mainly traced to Western, West-Central, and South-Eastern Africa), 12.5% Eurasian lineages, and 0.5% Amerindian lineages. We highlighted disequilibria between European paternal contribution (44%) and European maternal contribution (7%), pointing out an important sexual asymmetry. Finally, the estimated Native American component was strikingly low and supported the near-extinction of native lineages in the region. Discussion:We confirmed that all historically known migratory events indeed left a visible genetic imprint in the contemporary Caribbean populations. The data gathered clearly demonstrated the significant impact of the transatlantic slave trade on the Guadeloupean population's constitution. Altogether, the data in our study confirm that in the Caribbean region, human population variation is correlated with colonial and postcolonial policies and unique island histories.

Genetic ancestry, admixture, and population structure in rural Dominica

“…We identified 10–13% less European ancestry among X chromosomes compared to autosomes of sampled women, suggesting that there was a higher proportion of European male than female ancestry among the community’s founders. This is consistent with historical accounts and genetic data that show asymmetrical admixture reflecting colonial power imbalances across the Caribbean [ 8 , 28 ], and there is prior evidence for relatively higher proportions of non-African male admixture in Dominica based on Y chromosome short tandem repeats [ 7 ]. However, we interpret our X chromosome estimates with caution given the small number of generations (5–6) since initial admixture in this community (Tables 3 and 4 ).…”

“…The dating of this admixture estimate in the mid-19th century closely follows emancipation in Dominica in 1834, supporting oral accounts that communities in this area were formed by newly emancipated people seeking sustained refuge along the island’s steep eastern coast [ 6 , 14 ]. Although the largest proportion of extant genetic variation in Bwa Mawego, Dominica is associated with African reference populations, followed by European and Amerindian mixture proportions (Tables 2 and 4 ), we detected significantly more Amerindian admixture in this area than has been identified elsewhere in the Lesser Antilles [ 7 , 8 , 12 ]. This reflects the locally variable impacts of colonialism throughout the Caribbean that continue to impact populations into the present.…”

“…Dominica’s unique admixture composition and relatively high proportion of indigenous Amerindian genetic ancestry [ 26 ] highlight the locally variable impacts of colonial forces and specific ecologies in the Caribbean. This is further emphasized by the near absence of Amerindian ancestry found among the Guadeloupe archipelago neighboring the island to the north [ 8 ]. While such absences promote narratives of indigenous “extinction” in the Caribbean, our findings from rural Dominica demonstrate that, as has been found among other living groups in Cuba and Puerto Rico, indigenous lineages survive into the present and are highly variable in their distributions [ 3 ].…”

“…The Commonwealth of Dominica is a mountainous island nation in the Lesser Antilles where exceptionally steep terrain is historically known to have provided refuge for people of indigenous and African ancestries fleeing colonial violence and enslavement between the late 15 th and mid-19 th centuries [ 5 , 6 ]. Mitochondrial and Y chromosome data indicate that uniquely higher proportions of indigenous Amerindian genetic lineages have survived in Dominica than among neighboring Caribbean islands, but genome-wide patterns of extant variation in Dominica have yet to be characterized [ 7 , 8 ]. We assess population structure and genetic ancestry in a horticultural community on the eastern coast of Dominica using high-density single nucleotide polymorphism (SNP) and genealogical data to inform post-colonial history in this unique region with biological evidence.…”

Y Haplogroup Diversity of the Dominican Republic: Reconstructing the Effect of the European Colonization and the Trans-Atlantic Slave Trades

“…2015 ; Poznik et al. 2016 ; Mendisco et al. 2019 ), in line with a coastal origin of slaves rather than Sahelian.…”