Figure 4

Overlap of volumes in PC space differed in pairwise species comparisons. (a) The feature volumes of DF (green) and GW (purple) syllables show minimal overlap (< 1%). DF songs are composed of harmonic syllables with low fundamental frequencies and slow spectrotemporal modulations, while GW songs have high-frequency, tonal syllables with fast temporal modulation. (b) BF (blue) and RF (red) songs have highly overlapping volumes. Specifically, 92% of RF acoustic feature space is shared with BFs. RFs share fast-to-moderate spectrotemporal modulations and variable entropy between harmonic banding with the BFs. RF syllables tend to be higher in frequencies, lower in harmonic band number, and have more upsweeps than BF syllables. (c) Hypervolume overlap indices quantifying the percent of Species X’s volume in Species Y’s volume. Note that values depend on which species in a pair is X and which is Y, and volume overlap can be asymmetric: a large proportion of Species X’s volume may overlap with Species Y, but a small proportion of Species Y’s volume may overlap with Species X’s volume.