Fig. 3

Time of first transcription of 81 genes in Sp vs Lv. The time of transcriptional activation of Sp is recorded along the X axis and time of gene activation of Lv along the Y axis. (The Lv times are doubled to normalize developmental progression based on temperature differences in culture.) The black circles are genes that are expressed at the same time (within ± 2 h) in both species, given that allowance for temperature normalization. The circles above or below the gray area on either side of the diagonal line represent genes that are heterochronically expressed between the two species. Those circles above the line are genes that are activated earlier in Sp, relative to time of activation in Lv. Circles below the line represent genes that are activated earlier in Lv relative to Sp. The circle at 0,0 represents 20 genes that are expressed maternally in both species. The gray box represents 2 h above and below the diagonal line. Genes within that box are considered to be expressed at the same developmental times in both species allowing for natural variation and/or sensitivity of detection to account for deviations from the diagonal line