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Polymorphic Alu insertions in six Brazilian African-derived populations
Nelson Henderson Cotrim1, Maria Teresa B M Auricchio, João Pedro Vicente
1Centro de Estudos do Genoma Humano, Departamento de Biologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil.
Summary
Genetic studies of Brazilian quilombos reveal distinct African ancestry. These populations exhibit genetic drift and founder effects, acting as semi-isolates with significant internal variability.
Area of Science:
- Population Genetics
- Human Evolutionary Studies
- Anthropology
Background:
- Over 25 African-derived populations, known as quilombos, are situated in Brazil's Ribeira River Valley.
- Understanding the genetic makeup of these historical communities offers insights into population dynamics and ancestry.
Purpose of the Study:
- To genetically characterize six quilombo remnants in the Ribeira River Valley using Alu polymorphic loci.
- To compare the genetic variability and differentiation of these quilombos with other global populations.
Main Methods:
- Analysis of four Alu polymorphic loci (APO, ACE, TPA25, and FXIIIB) in individuals from six quilombos and São Paulo city.
- Calculation of genetic variability indexes (Fst, Gst) and construction of neighbor-joining trees and principal component analysis.
Main Results:
- Quilombo allelic frequencies align with African-derived populations from the Americas.
- Higher genetic differentiation (Fst, Gst) observed in quilombos compared to most populations, but lower than Amerindian groups.
- Neighbor-joining and principal component analyses show clustering with African and European populations, with one isolate.
Conclusions:
- Brazilian quilombos exhibit genetic characteristics of semi-isolates, influenced by genetic drift and founder effects.
- These populations demonstrate greater genetic variability within than among groups.
- Quilombos show gene flow patterns consistent with other African-derived populations globally.