Fig. 1.

GC content is weakly associated with eusocial specialization in the honey bee Apis mellifera. (A) Comparison of third codon position GC content (GC3) based on gene expression differences between brains of queens and sterile workers. According to Wilcoxon rank-sum tests, worker-biased genes differ significantly in GC3 from nonsignificantly biased genes (P < 0.0001) and queen-biased genes (P = 0.0218). (B) Comparison of GC3 based on gene expression differences between brains of drones and workers. Worker-biased genes exhibit dramatic, significant differences in GC3 compared with nonsignificantly biased genes (P < 0.0001) and drone-biased genes (P < 0.0001), but differences of this magnitude are not inherent to the female caste specialization that underpins eusocial behavior shown in A.