Heat map of differentially expressed genes. The figure shows row centered and scaled data from 419 genes identified by directly comparing transcript abundances between axolotls and tiger salamanders. The columns correspond to individual GeneChips with the prefixes AM and AT denoting axolotl GeneChips and tiger salamander GeneChips respectively. Time points correspond to days post hatching and are denoted by numbers followed by a letter (e.g., AM08_42C.CEL corresponds to an RNA pool derived from axolotls sampled at 42 dph). The dendrogram to the left was obtained via hierarchical clustering of a pair-wise distance matrix that was calculated as |1 - r|, where r = Pearson's correlation coefficient.