Anuran serenades in Neotropical forests: The evolution of advertisement calls in glassfrogs.

Anurans emit advertisement calls with the purpose of attracting mates and repelling conspecific competitors. The evolution of call traits is expected to be associated with the evolution of anatomical and behavioral traits due to the physics of call emission and transmission. Furthermore, vocalizing might imply a trade-off with investment in parental care. We investigated the association between body size, calling site, parental care and call properties (call duration, number of notes, peak frequency, frequency bandwidth and call structure) of the advertisement calls of glassfrogs (Centrolenidae) using phylogenetic comparative methods. We also explored the tempo and mode of evolution of these traits and compared them with those of three morphological traits associated with locomotion and feeding. We generated and compiled acoustic data for 72 glassfrog species (46 % of total species richness), including representatives of all genera. We found that almost all acoustic traits have significant, but generally modest, phylogenetic signal. Peak frequency of calls is significantly associated with body-size, while call structure is significantly associated with calling site and paternal care. Thus, the evolution of body size and calling site could constrain call evolution. The estimated disparity of acoustic traits was larger than that of morphological traits and the peak in disparity of acoustic traits generally occurred later in the evolution of glassfrogs, indicating a historically recent outset of the acoustic divergence in this clade.