Fig. 8. Knollenorgan tuning estimated by upside-down plots of amplitude spectra of revcor filters for type I individuals (left) and type II individuals (right). Revcor filter spectra were smoothed using an unweighted three-point average, scaled the same with respect to power (20 dB scale bar indicated) and shifted by an arbitrary amount along the vertical axis to avoid overlap. A circle highlights the best response frequency of each unit. Each spectrum corresponds to a unique receptor. Knollenorgans in the type I morph: specimen 1, SL=94.5 mm, adult female or non-breeding male (blue); specimen 4, SL=107 mm, dominant male (green); specimen 3, SL=92 mm, adult female or non-breeding male (red). Knollenorgans in the type II morph: specimen 6, SL=76 mm, adult female or non-breeding male (blue); specimen 2, SL=87.5 mm, adult female or non-breeding male (red); specimen 5, SL=94.5 mm, adult female or non-breeding male (green). One star indicates receptors described in Fig. 9A,B; two stars correspond to Fig. 9C,D.