Using Q10: Can growth rates increase linearly with temperature?

For autotrophic and heterotrophic protists, we reviewed growth rate versus temperature data (92 cases, 74 species, 36 studies), using non-linear curve-fitting methods to determine whether relationships were linear. Of the 92 cases, 67 contained sufficient data for analysis; 61 did not significantly differ from a linear response (mean slope: 0.064 0.005 d -1 C-1 ). Of the 25 cases that were not statistically analysed, 18 appeared linear. The mean slope of the 79 data sets considered to be linear was 0.07 0.005 (d -1 C-1 ). We suggest that growth rate usually responds linearly to temperature, the use of Q 10 may be inappropriate, and a Q 10 of 2 may arise due to this linear relationship and inappropriate experimental design.