Table 3 The number of total species, still-water species (SW), still-water species that have or not have prominent frequency modulation (SW FM vs. SW NonFM) and harmonic (SW H vs. SW NonH), flowing-water species (FW), flowing-water species that have or not have prominent frequency modulation (FW FM vs. FW NonFM) and harmonic (FW H vs. FW NonH) across Ranidae or Bufonidae