In order to evaluate the possible independent contribution of ethnicity more carefully, variance component analysis of the expression variation was performed. Within Agadir alone, neither ethnicity (modeled as the second eigenvector of the genotype data, gPC2) nor gender have a noteworthy impact on the principal components of the expression variation, as shown by the bar charts in Figure 3b. However, in the total dataset there is some evidence for a contribution: Figure 3c shows that when fit jointly with location, the ethnicity, ethnicity-and gender-by-location interaction terms make a substantial contribution to the expression profiles.
