Hierarchical clustering analysis of the 56 differentially expressed ribosomal protein genes between Apis mellifera and Apis cerana . For each gene, the TPM mean value of the two biological replicates at each stage was used to calculate the expression ratio between Apis mellifera and Apis cerana, i.e., TPM
/ TPM Apis cerana. If the value of TPM
was 0, it was replaced by 0.01. This ratio was log2-transformed and used for clustering analysis, which was performed using the Cluster 3.0 and Treeview programs. Red represents up-regulated expression in Apis mellifera. Green represents up-regulated expression in Apis cerana.