Fig. 2. Effects of male experimental manipulation on power spectra of rev displays. (i) Oscillogram of rev display; (ii) power spectra of rev display; (iii) experimental treatment. (A) Control treatment. (B) Palpal treatment. Experimental treatment consisted of waxing the tibio-cymbial joint of the palp, rendering the joint immovable. High frequencies were attenuated following manipulation. (C) Abdominal treatment. Experimental treatment consisted of waxing the cephalothorax–abdomen joint, rendering the joint immovable. Low frequencies were attenuated following manipulation. (D) Palpal and abdominal treatment. Experimental treatment consisted of waxing the tibio-cymbial joint of the palp and waxing the cephalothorax–abdomen joint, rendering both joints immovable relative to each other. All signals were attenuated following manipulation.