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Population substructure and isolation by distance in three continental regions
1Department of Anthropology, The Pennsylvania State University, University Park 16801, USA. elise.eller@anthro.utah.edu
American Journal of Physical Anthropology
|February 13, 1999
Summary
Geographic distance explains nearly 60% of worldwide human genetic diversity, suggesting populations haven't reached equilibrium. Analysis of short tandem repeat (STR) data reveals patterns potentially reflecting demographic history and population expansions.
Area of Science:
- Population Genetics
- Human Evolutionary Studies
- Bioinformatics
Background:
- Population substructure arises from isolation by distance and divergence from shared ancestry.
- Isolation by distance can obscure population history as populations approach migration-drift equilibrium.
- Diverging populations accumulate genetic differences over time.
Purpose of the Study:
- To quantify the extent to which isolation by distance explains worldwide genetic diversity using short tandem repeat (STR) data.
- To investigate patterns of genetic diversity at intercontinental and intracontinental levels.
- To explore implications for migration-drift equilibrium and population history reconstruction.
Main Methods:
- Analysis of 60 tetranucleotide short tandem repeat (STR) data from Jorde et al. (1997).
- Application of Slatkin's R(ST) measure for population substructure.
- Utilized principal components analyses and Mantel tests to assess genetic diversity patterns against geographic distance.
Main Results:
- Geographic distance accounted for approximately 60% of worldwide interpopulation genetic relationships.
- Intracontinental correlations were lower, suggesting populations have not reached migration-drift equilibrium.
- Observed excess heterozygosity in Africa, potentially due to a larger effective population size, and differing patterns between heterozygosity and allele size variance.
Conclusions:
- Geographic distance is a significant factor in global human genetic variation.
- STR data contains information valuable for reconstructing population history.
- Contrasting patterns in heterozygosity and allele size variance may indicate different timings of population expansions.
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