Heat map of K-means clustering of 1175 variably expressed genes in four developmental stages. Clustering was done using Cluster 3 software (clustering type: K-means clustering, Distance metric: Pearson correlation). The colors in the map display the relative values of all tiles within four selected developmental stages; Green indicates the lowest expression, black indicates intermediate expression, and red indicates the highest expression. The numerical values give the actual values on a log 2 scale, which are associated with each color. The color scale bar is shown at the top right corner of the figure. Genes were grouped into four clusters on the basis of the expression similarity. The number of the expressed genes and the percentage in each cluster are indicated.