highly significantp < 0.001
The cubic spline fit of pterin relative fluorescence was highly significant for both female and male flies (Females: F 9 = 24.58, p < 0.001, with the fit explaining 49.5% of the variance; Males: F 9 = 10.87, p < 0.001, with the fit explaining 43.3% of the variance) indicating a strong seasonal effect.