FIGURE 18. Interpretation of advertisement call differences: (A) Spectrograms and oscillograms of calls of two allopatric frog species without any significant differences (evidence for species-level divergence by molecular genetics and tadpole morphology; Vences et al. 2010a). (B) Moderate structural call differences of two allopatric populations currently assigned to the same species. The calls of Blommersia wittei from Sambava and Andrakata are composed of clicking notes of a metallic sound, whereas at Nosy Be, Benavony, and Montagne d'Ambre, notes contain pulses and calls exhibit less distinct inter-note intervals. Spectrograms produced with CoolEdit Pro at Hanning window function, 256 bands resolution.