Fig. 1. Division of labor in honey bee colonies and brain gene expression: age-related, behavior-related, and genetic differences. Principal component analysis (PCA) was performed using brain gene expression measurements for all 5736 genes from all 72 bees in Experiment 1. Individual bees are plotted as a function of PC1 and PC2 (A) or PC1 and PC3 (B). Ontogenetic group and subspecies are indicated in legend. Cumulative variance explained by PCs is indicated on axis (see Fig. S2 and Table S1 for all PCs).