Fig. 2

Cell cleavage period scales in a similar non-Arrhenius way across different early ectothermic embryos. A We examined the timing of the early cell cycles in 5 different species: C. elegans and C. briggsae (from ref. 31), D. rerio (this work), X. tropicalis and X. laevis (this work). The three vertebrates and the two nematodes span a broad range in evolution. B Median cleavage period in function of temperature for the early cell cleavages (all pooled) for the 5 different species. Optimal fits using a double exponential (DE) function are overlayed. C The in vivo range of viable early cell cycles in the different species, including their thermal limits and optimal temperature at which they reach a minimum cell cycle period. Their corresponding apparent activation energies and Q10 at 20 °C are shown in the table. Additionally the environmental range is indicated for all five organisms101,102,103,104. D Using the best DE fit, the local Q10 value is plotted in function of temperature. E The median cleavage period in function of temperature for X. laevis is fitted using different functional forms: single exponential Arrhenius (SE), double exponential (DE), quadratic exponential (QE) and a power law-exponential (PE) function. F The goodness of fit (using mean square error, MSE on the logarithms of the periods) of the alternative functional forms to the experimental data for X. laevis in two different temperature regions: 12–21 °C and 9–29 °C. G. Goodness of fit, similar as in panel F, but now for all different species over their whole measured temperature range. Source data are provided as a Source Data file98.