Fig. 2

Vole brain gene expression varies consistently by species and region. a Matrix of Poisson distances between each sample based on gene count data. Darker shades are more similar. Color key to the left shows sample type for each row. Hierarchical clustering trees show that samples split first by species, then by brain region. b Principal component analysis of sample gene count data shows first principal component (PC1) that separates samples by species and accounts for 39% of sample variance. Second principal component (PC2) separates samples primarily by region and accounts for 34% of variance