Fig. 4

Model parameters are obtained by fitting the power spectrum. a Examples of data power spectrum (black line) and fit (red diamonds) for a wild type fly measured in LD (top) and DD (bottom). In the LD data, the 12 h peak is stronger than the 24 h peak and was therefore used as the reference peak in the fit. Comparison of model and data power spectra for low \(T\) shown in the inset. For low values of the period, the model predicts peak height \(H(T) \propto T^{4}\) (inset, dashed line), a behavior not shown by the data. b Errors in peak height estimation from 10 flies (mean error ± standard deviation). On average, peak heights are estimated with error of 10 % (dashed lines) or better. c Parameters obtained from a are used to construct model of fly activity. Data (black line) shown in 20 min bins; day/night shown with white/black bars for LD and subjective day/night shown with white/grey bars for DD