Fig. 2.

RNA-seq sample heatmap and hierarchical clustering based on the expression of the 9461 orthologous genes across the four species. Pairwise similarity between samples is computed as the Pearson correlation between the base 10 logarithm of the expression (TPM) of the 9461 orthologous genes. These similarities are plotted as a heatmap, where samples appear both as rows and columns and are labelled by their species and tissue and the sex of the animal. The color of each heatmap cell also reflects the similarity (Pearson correlation) between each sample pair (the lighter, the higher). Hierarchical clustering is performed using one minus the squared Pearson correlation as a distance and the complete linkage aggregation method