Purring Crickets: The Evolution of a Novel Sexual Signal

Abstract

Opportunities to observe contemporary signal change are incredibly rare but critical for understanding how diversity is created and maintained. We discovered a population of the Pacific field cricket (Teleogryllus oceanicus) with a newly evolved song (purring), different from any known cricket. Male crickets use song to attract females from afar and to court females once near. Teleogryllus oceanicus is well known for sexual signal evolution, as exemplified by a recent signal loss. In this study, we characterized the new purring sound and investigated the role of the purr in long-distance and short-distance communication. The purring sound differed from typical ancestral calls in peak frequency, amplitude, and bandwidth. Further, the long-distance purring song facilitated mate location, though the role of courtship purring song is less clear. Our discovery of purring male crickets is an unprecedented opportunity to watch the emergence of a newly evolved sexual signal unfold in real time and has potential to illuminate the mechanisms by which evolutionary novelties arise and coevolve between the sexes.

Keywords: Teleogryllus oceanicus; evolutionary novelty; rapid evolution; sexual signal.