In the original article, there was a mistake in Figure 1 as published. There is a mistake in the formulas in Figures 1Aa,b. The corrected Figure 1 appears below.

In the original article, there was an error. There is a mistake in the sigmoid formula, we wrote log(mRNA(t))=a-bec(t-ti) and the correct formula is: log(mRNA(t))=a-b1+ec(t-ti)

A correction has been made to the section Scaling developmental rates between related species, Paragraph Number 3:

Most zygotic genes have a clear activation curve that can be well fitted with the following sigmoidal function: log(mRNA(t))=a-b1+ec(t-ti) (Figure 1Aa; Yanai et al., 2011). Here a is the final expression level, b is the increase in level relative to the basal expression level, c is the slope of the curve, and t_i is the initiation time, that is, half-rise time, the time when the expression level is half of the total increase (Figure 1Aa). The initiation times of all measured genes in each species are estimated using this function. The initiation times in one species is then plotted relative to gene initiation times in the other species. In Figure 1Ab we use published measurements of the initiation times of 22 developmental genes in the sea urchins species, Paracentrotus lividus (P. lividus) and Strongylocentrotus purpuratus (S. purpuratus) (Materna et al., 2010; Gildor and Ben-Tabou de-Leon, 2015). These two species diverged from their common ancestor about 40 million years ago and are geographically separated: S. purpuratus occupies the west coasts of the Pacific Ocean and P. lividus occupies the east coasts of the Atlantic Ocean and the Mediterranean Sea. Yet, despite the genetic and geographic distance their embryonic body plan is highly similar. We measured gene initiation times in the two species based on their expression kinetics up to late gastrula stage [30 hpf in P. lividus and 48 hpf in S. purpuratus (Materna et al., 2010; Gildor and Ben-Tabou de-Leon, 2015)]. The trend-line gives the linear relationship between the developmental time in S. purpuratus and P. lividus: T_Sp = 2.42+1.037 × T_Pl. Here the constant, 2.42, corresponds to the shift in the maternal to zygotic transition that is about two and a half hours later in S. purpuratus compared to P. lividus. The slope, 1.037, is a little higher than 1, since the developmental rate in S. purpuratus is slower than in P. lividus, possibly due to the lower culture temperature of S. purpuratus [15 vs. 18°, (Gildor and Ben-Tabou de-Leon, 2015)].

The authors apologize for this error and state that this does not change the scientific conclusions of the article in any way. The original article has been updated.