Speaker
Description
Sexual signals play a crucial role in driving speciation and evolution. A key function of these signals is to communicate species identity. Signaling species identity creates reproductive barriers by enabling recognition of conspecific mates and discrimination against incompatible heterospecifics. The signals and signal preferences can evolve rapidly in speciation events, yet research has largely focused on the signal and not the associated preference. However, the content in the signal only sets an upper bound for information transmission in a communication system, whereas signal preferences reveal which information is actually used in evolution.
Here, we examine the calling songs of crickets, a species-specific signal with structure on multiple timescales, and their preferences across a group of 15 to 40 species. We find that the calling songs of 40 species carry sufficient information for species discrimination. Signal preferences enable conspecific recognition and heterospecific discrimination but exploit only a small fraction of the information from the song. These results suggest that these signals could support additional species, but that females only use information sufficient for species discrimination. The preferences may have evolved to balance information usage for heterospecific discrimination and robustness for conspecific recognition. Overall, by examining the coevolution of the sender and the receiver in a species-specific signal, our results reveal the processes and limitations of signal evolution.
