Principal Coordinate Analysis (PCoA) on the acoustic dissimilarity matrix.

<p><b>A</b>: Eigenvalue bar plot. <b>B</b>: Results of PCoA applied to the acoustic dissimilarities among recordings with factor “Time” as a supplementary variable subsequently projected on the map. Projection along the axes 1 and 2. <b>C</b>: Results of PCoA applied to the acoustic dissimilarities among recordings with the spatial factor “Site” (A: Aoupinié, K: Koghis, M: Mandjélia). Projection along the axes 3 and 4. The dispersion ellipses surround the position of a time period (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0065311#pone-0065311-g004" target="_blank">Figure 4A</a>) or of a site (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0065311#pone-0065311-g004" target="_blank">Figure 4B</a>) providing an index of the dispersion around the time/site centroid (67% of recordings collected at a given time or at a site are expected to be in the associated ellipse).