Genetic ancestry, admixture, and population structure in rural Dominica

Area of Science:

• Population genetics
• Human evolutionary studies
• Caribbean anthropology

Background:

• The Caribbean exhibits significant genetic diversity shaped by complex historical factors.
• Dominica, a Lesser Antilles island, has unique migration and isolation patterns.
• Understanding genetic admixture informs post-colonial historical narratives.

Purpose of the Study:

• To provide genome-wide insights into genetic ancestry and population structure in Dominica.
• To investigate family-based clustering and admixture proportions.
• To date recent admixture events in a Dominican community.

Main Methods:

• High-density single nucleotide polymorphism (SNP) data and genealogy.
• fastSTRUCTURE for clustering and Human Genome Diversity Panel for references.
• TreeMix for migration modeling and ALDER for linkage disequilibrium decay analysis.

Main Results:

• Genetic structure was distinguished from admixture proportions (African, European, indigenous Amerindian).
• Admixture was dated to approximately 5-6 generations (~160 years) ago.
• Dominica's ancestry shows higher indigenous and lower African proportions than other Caribbean islands.

Conclusions:

• Genetic results align with local historical accounts of mid-19th century settlement.
• Post-colonial admixture and family structure reflect localized historical and ecological impacts.
• Further research on diverse Dominican groups is needed to fully understand the island's history.