Detection of differential gene flow from patterns of quantitative variation

Area of Science:

• Anthropological Genetics
• Population Genetics
• Quantitative Genetics

Background:

• Microevolutionary forces shape genetic diversity within and between populations.
• The Harpending-Ward model (1982) assesses gene flow by comparing observed and expected heterozygosity.
• Gene flow influences population heterozygosity relative to regional allele frequency centroids.

Purpose of the Study:

• To extend the Harpending-Ward model for analyzing microevolutionary forces using quantitative traits.
• To assess the impact of differential external gene flow on genetic and phenotypic variance.
• To develop methods for estimating the genetic relationship matrix (R) from quantitative traits.

Main Methods:

• Extended the Harpending-Ward model to quantitative traits assuming an equal and additive effects model of inheritance.
• Compared observed and expected genetic or phenotypic variance to evaluate external gene flow.
• Utilized phenotypic covariance matrices as a conservative approach when genetic data is limited.
• Developed new methods for estimating the genetic relationship matrix (R) from quantitative traits.

Main Results:

• The extended model allows for the assessment of differential external gene flow using quantitative trait variances.
• Analyses of dermatoglyphic and anthropometric data from Nepal and Ireland yielded interpretable results.
• Both univariate and multivariate analyses aligned with known historical patterns of gene flow.

Conclusions:

• The extended Harpending-Ward model provides a robust framework for inferring gene flow from quantitative trait data.
• This approach is applicable to diverse datasets, including anthropometric and dermatoglyphic measurements.
• The findings contribute to understanding microevolutionary processes in human populations.